Any body know if the procomp aluminum big block heads take standard size head bolts? And what size are the pushrods for the 1.6 rockers on these heads (flat tappet hydrolic cam)?

On a motor that I set up about a year ago, The push rods were 9.45" long push rods. I recommend getting a push rod measuring tool and measure what length you need.You can get one from 440 Source for about $25.
Yes, they use standard head bolts/ studs.

In theory they use std length bolts, but the long bolts should be appx 1/4" longer to avoid a short thread engagement in the block which can tear out the threads. The bolts should also have smaller heads than the std 11/16 to get access with the tool. I know it the hard way....
Best is to bottom thread all holes in the block and then have longer bolts also the short ones... Check what you can get of SBC / BBC stuff, I have some of those that worked OK.

What brand rocker are you running? I Think my pushrods came in at 9.35" with hughes 1.6s. I used an ARP head bolt kit designed for the Eddy Victors. The bolts have a smaller head than a stock bolt. Not sure about the length.