Gen VI head swap

Looking to bump performance up a few notches by ditching the L29 vortec heads and going with some older closed chamber ovals. I do not want to open up the bottom end since it is fairly low miles and runs solid as is. My budget is $1000 total expenditure.

My understanding after a few searches is that I can run Mark IV heads on my Gen VI block with head gaskets that match the heads. Is there anything else I need to be aware of. I know I will need different rocker arms, but what about push rods?

For heads, I have found a set of bare 290 castings but I think the guy wants too much for them... $250. By the time I buy valves, springs, keeper and locks and the required machine work I'm guessing it would cost over $1000, which kills my budget

Another option I've found is a set of 390 heads that have already been built up with 2.19/1.88 vales and some 'mild' porting for $550. I would still need to get a set of springs to match my HR cam, but these seem to be the better buy.

Advice and opinions welcome.