A friend of mine wants to upgrade his 69 Polara convert from a 2bbl to a 4bbl,I told him he should be replacing his timing chain & upgrade his cam also,I doubt he will want to replace his springs even though he should be having the heads reconditioned,what would be a good mild cam for his bone stock 69 383,Im not sure what intake & carb he already bought but I will find out.

Summit house brand cam. cheap/works well/good reviews. EDIT good advice on the tchain & I would adv it 4 deg. an eddy 1406 would work good on the stock intake & get the strip kit for it. the most inefficient area that needs the most attention would be the exhaust, a pair of 68-70 HP manifolds (pricey but good) and a good mandrel bent 2&1/2" ex systemwith an X pipe with dynomax (sp) turbo muffs and cherry bomb glasspacks alongside the springs for addit'l muffling would work very well. dial in the dist subsystems in order when done.

Do a leak down test while the rockers are off.Best way to know if you have a good sealed long block. It alleviates any question before you do all your work.We are doing a '67 383 Newport now that was to be a cam /intake swap.It has 516 heads,a couple valves were leaking badly and one cylinder/rings had a bit of pressure loss.Out for a rebuild now,swapping on 452 heads and using a Howards .434" lift cam.
RT

Id check and likely replace the springs before thinking about a cam upgrade.

x2...

Old heads, unleaded gas....... Often look like this:
(This pic is a BBC, but I've seen many mopars just as bad)

The poor mans quick check is a straight edge across the tops of all the valves.
If the ex tips are noticeably higher than the intakes, you likely have some valve seat recession going on.

As for a cam for that application......
The smaller Summit cam, or a Howard's MC720931-11, or MC720031-12.
All would require a spring upgrade from the OE 2bbl spring.
Good time to replace the valve seals as well.

I've been talking with & encouraging him to go about it the right way other wise he's just throwing his money away,going to do a cyl.comp.& leak down test this weekend first to determine eng. soundness,he already ordered a holley 4160 600 cfm carb & Weiand action+ intake,could have found a good used dual plane intake but he jumped the gun before letting me know his intentions,he needs to upgrade to elect.ign.also.

I had a guy wanting to put the Mopar 292/0.509" in a stock low compression 440. Valve spring seat pressure was between 70-75#.
I think we used the valve springs that came on some 440 source stealth heads (that were changed for the cam in another car) on his stock 906 heads. I don't recall if we talked the owner into a better suited cam, but we did use the thin steel shim head gaskets to try increasing the compression ratio.

The main issue I run into when using just about any aftermarket spring on stock heads with stock retainers is........ They don't fit either the head or retainer very well at all.

Even the OE springs are a bit sloppy, but not as bad as the typical 1.50-1.55 spring.

When I have the option to "do it right"....... Then I machine the heads for spring cups and use aftermarket retainers.

The OE type hp spring option is the low buck approach..... And also limits cam choice quite a bit.
But it would be a perfectly adequate solution in this case IMO.

The OE retainer has a step diameter of 1.00, and a spring from a bb rpm head has an ID of 1.130, so the retainer can swim around with .130 worth of movement.