If you're running hydraulic lifters you need a hydraulic flat tappet cam and correct length push rods. If you're still running the factory iron adjustable rockers, make sure your lifter preload is correct as well or things will go bad quick.
I LOVE mechanical cams, only reason I'm getting away now is that this short block I scored has brand new roller hydraulics, so I had a roller hydraulic cam ground, otherwise I'd be running mechanical lifters still.
I have to agree, but the easiest and cheapest way is to get the rockers, shafts, and pushrods from any non roller 318 or 360. Buy your cam, lifters, and springs and just bolt it together. Check for interference between the rockers and the springs and retainers.