There was a lot of horsecrap in the few replies, with gems in some of the followups.
Here's what I know:

Any number of 360s have hit the 400hp mark with stock heads.

The 308 heads have about the same intake ports as a 360 smog head. Their exhaust ports are much better. They work best with a single pattern cam. Too much exhaust duration lets potential horsepower out. Their combustion chamber is your basic Mopar open chamber, meaning no shape except for nearly round.

There is absolutely no need to use larger than stock valves on this head. What would help the most is work on the intake ports. There are a few articles floating around, the best IMHO being the one written by Steve Dulcich on porting smog heads. BTW, before you pay someone to port your heads, get a written quote. Those aftermarket heads may look better after you find out the head shop's total cost. Plus, most head shops don't like to work cast iron, it's dirty and takes longer.

Note that I didn't use the word "polish" anywhere above. That term went out of fashion when it was discovered that rough intake port walls make more power than shiny ones. Polish the combustion chambers and exhaust ports if you wish but it's a lot of work for very little gain.

Port matching and/or opening the ports to gasket size won't do a thing. If you have OCD, you should probably do it or else you'll be doing it later. Otherwise, just say "no".

Your factory roller cam is the best way to go. Regrind it. Call up Bullet and Delta and ask them how close they can get to a Comp XE268. Bullet may still be $120 for the regrind, Delta may still be $100. Not expensive at all.

Valvesprings should be replaced, I suggest Hughes 1110s. Also check the clearance between valve retainer and valve oil seal. There's not a lot of room in there. That's also why I picked the Hughes springs, they have about the least compressed height.

Let's talk about aftermarket heads. They will come out of the box flowing as much as a ported 360 head. But the prices! More than for a bigblock head. There's Enginequest's cast iron head, Edelbrock Performer heads, the ProMaxxhead, the Sidewinder and the Speedmaster (ProComp Electronics).Of those four, the edelbrock is the only Made in USA head. The Speedmaster heads are the least expensive and have much have quality castings, according to some posts I've seen. The benchmark for this group of heads is the Edelbrock Performer. The value leader is the Sidewinder head. It should take hundreds off the Edelbrock price. The Sidewinders are built to your specifications and should be ready to go out of the box.

R.