adding '302 heads to a '77 318

ive been doing a little research on raising the power of my '77 chrysler lebaron. it has the factory 318 with the 904 transmission.

currently i have:
`long tube headers (summit)
`dual exhaust (2.5" with flowmasters)
`weiand action plus dual plane intake
`MP electronic ignition conversion kit
`holley 4160 4bbl in a 600 cfm size (yes, i know its WAY to big, i didnt know about VE when i ordered it

here are my questions:

id like to put the '302 casting heads onto it to raise the compression a bit, being that they are of a closed chamber/heart shaped design. would i need to change the pushrod length at all? i was also looking at what thickness headgasket to use, any ideas? is there anything that i should do besides gasket match the intake to the heads? anything im missing?

with the raise in compression ratio, what size carb should i use? id like to stick with the holley 4160 series because they are the only carbs ive ever delt with...

thanks for the help in advance
-glen