Are there better headlights available for the 72 RR type of bulbs? I have standard halogens and they arent bad by any means. Put them on relays which helped alot.

But wondering if there is a brighter drop in bulb?

Aircraft landing bulbs, number 4537, but they really suck up the juice, and they are likely to blind oncoming traffic. 200,000 candle power (each), and you will need to adapt to the screw type connections on the back of the bulb. You will also have to file a groove for the alignment lug to orient it in the headlight bucket too. Had them in the bright position on my 69 Catalina and my 70 Datsun pickup. Relays are absolutely necessary. A much more reasonable brightness bulb is the old style Lucas lights, if you can still find them. No doubt they can still be imported from England, but they are probably way overpriced.

What I have in my 70 Challenger:
Hella Bi-Focal H1s for the lows, comes with DRL provision
Cibie parabolic H1s for the highs
Narva-Flosser Rangepower+50 H1 bulbs all around
Relays

Low beams have a bright white light with nice crisp cutoff lines. The Highs really light up the road.

"Crackedback" sells a relay kit that is completely plug and play. No need to cut up any of the existing wiring. I'd look into one of those.

He already has them on relays.

What did you use for wire sizing?

There are good and bad places to pull power for headlights. It makes a big difference in performance.

I did the relays and wiring per MAD wirings instructions.

The lights are bright, no comparison 2 b4. But, just wondering if there is a brighter lamp to be found.

Mad recommends 14ga which is exactly the same size wiring as original. IIRC. The only real benefit was shortening wire lengths and minimizing connections in the circuit.

Well...All I know is the lamps are as bright as some of my more "modern" cars.

Still want to know if better lamps can be found or if I will have to go to Hella type lamps.

Actually, you can get the Lucas lights pretty reasonably priced. Look up Rogers Motors: http://jollyrogersmotors.com/store/p/423-Lucas-H4-Headlamp-Pair-New.html. These are 7" lights but I am sure they can supply the smaller ones for a 4 headlight system. Very nice people to deal with, just give them a call.

We got two pairs of RHD 7" ones for our Landy's, with replaceable Halogen bulbs. I plan to get a pair of the 5-1/2 RHD outboard (low and high) headlights for the Road Runner when I can get it in the shop. Also got relay kits from them with the correct colour coding for the Landys, will see if it matches up to Chrysler colour coding, if not will go with the person on here. The LHD lights are actually $10 cheaper (good for the OP) but we drive on the left here so if spending the money we got the correct ones, the difference is in the lens, both use the same bulb.

Legal lights, not real likely.

There are some and they are very costly in most cases.

Check on Daniel Sterns site for a run down on legal lights.

The answer is probably yes with a little footwork. The problem is only that there has been a more limited market for the 4 lamp, 5.75" diameter systems.

If you have a run of the mill Wagner halogen sealed beams, there seems to be some agreement on Candlepower forums (which stays pretty much to evidence based opinions) that the GE Night Hawks are about the best sealed beams out there. So you might try those.

The other option is to change to a good quality seperate bulb and lamp housing system. The Lucas's linked above are that type of system.

For quality - Look for SAE/DOT and/or E-code marked lamp housings. That will assure you the lamp meets a minimum standard; (or rather that the manufacturer certifies it meets the standards.)
If available in your sizes (and I think they still are), you can't go too wrong with a Hella's "vision plus" line. Even if its just for the hi/low. These meet both US and European specs and do a great job of putting more light down on the road.
Cibie and Bosch also have good lamps of this nature. Not sure about availability in the 5.75" round 4 lamp system like your RR has, but worth investigating. Just make sure you get them for the correct side of the road!

Along with the housings, you'll want good quality bulbs. Poke around on Candlepower forum for which ones. A couple of the Phillips and Narva bulbs seem to be really good with essentially the same current draw as stock and little of expected life.

Took a look around on the 'net.
Looks like the sealed beam Nighthawk may not be available for the 5.75".

According to Virgil's Best headlight for vintage corvair posts (he's a lighting engineer or scientist in real life), photometrics are better on an older NOS quality non-halogen sealed beam than stuff that's available today.

For replacing the H5006 (Hi/Lo) the Hella bi-focus mentioned above may be the best option. Hella H4s are also currently available. These listed here are not SAE even though the seller calls them "Vision plus". E-code is perfectly fine nowadays. This used to be an issue especially in states that used mechanical headlight testing.

For H5001 replacement (High Beam) there's H1 bulbed Hella's
Hella H1 at Summit (pair) or you can buy individually and use the bulb of your choice.

I will say that a really good lamp definately makes a difference. Unfortunately there's a lot junk out there and both good and bad stuff is marketed with a ton of hype. It's not just about being brighter, its about getting the light directed in the correct place. One advantage of anything made to meet E-code is that the low beam cuts off so as to reduce glare in rain and fog.

Some 5.75" H5006, H4 and H1 Photometrics at Dan SternLighting