The cam going flat was probably the reason everything loosed up, not the victim. No need to go double roller unless you're going to run a big ass roller cam with stiff springs.
Get your machinist to find the worst cylinder and let me know the loosest part of the loosest cylinder.
the original springs are probably what caused the cam to take a beating in the first place (if they have a cup on the bottom of the spring, they probably are stock)
Bowl porting the heads are well worth the money. No need to go berzek spending money on them. You have a turbo to stuff air through the ports.
Back cut the stock exhaust valves, or get a set of SS Ferrea valves. With the Ferrea's you can run exhaust seals.
Make sure to pull EVERY oil galley plug out of the block and CLEAN THE LIVING SHIT out of EVERY nook and cranny in the block.....
then do it again. Cam debris can hide in corners and cause you to do this again.
oh, yeah. NEVER use your existing oil cooler again.