66-73 stock small block heads?????

Bucky Jones said
Where can one find scripture and verse on specifications, fitment, interchangibilty and cannibalization of 273/318/340 heads, blocks and exhaust manifolds/ headers???
Ex: X vs J?
273 vs 318 vs 340 exhaust ports/ header fitment?
valve/cam differences?
optimum cams/heads/exhaust vice 273/318/340?
Is there a matrix chart or computer program in captivity somewhere?
I had a new, STOCK, 1970, 340, 4spd Duster in Germany and it would fly up and down the autobahn. It would go from 0-130 mph in no time and would purr like a kitten at idle. Perfect setup although a Thermoquad and 1 or 2 more gears would have been cool! Mopar had that engine right. I put headers on it when I got it home but did not make much difference. I do not know the specs on that engine but I would love to build one just like it or a 275+HP 273 to put in my 67 Formula S. I just need that scripture and verse.
1972 was the beginning of the end of the powerful stock small block Mopars.
Comments? Suggestions?
Thanx

The old Chrysler Racing manual had an untouched head pecking order, when you could not port for Stock and Super Stock Class racing. Prine is pretty much right in general, except the 70-71 340 J heads had 2.02 intake valves. The best heads were X heads, then J / O / U, then the next in line etc. They got progressively worse till the 308 castings. However once you start porting there is not much difference, not that I'm a porter, I just clean up the bowls, gasket match the ports but leave the bottoms untouched, equalize the chambers within .2 cc and go. Early heads rarely crack, smog heads should always be magged. I've given up on finding uncracked 308's and I'll never run aluminum heads. X's, J's, and 587's are fine with me. The 587's and up had hard exhaust seats. The general pecking order is the same for the small port 273 / 318 heads. The older the better. Personally 340 engines were pretty much perfect, HP 273's next. 360's and 318's last although the 74 HP 360 was pretty good. They all have pluse's and minus's TQ carbs and manifolds are the best street induction, the trick is to find a good one now. I guess the good ones are all about 40 years old. I still like the 340 cam, but I drop the compression from the 68 to 71 340's. All Chrysler small blocks can be made to run very well. Some have all the good parts to begin with.