what bhp are you aiming for?
what exhaust housing do you have on your turbo? .48, .55 or .63

standard mahle pistons are more than capable, they will easily handle 500hp, and get valve cut outs

standard head bolts are fine as long as genuine ford ones, alot of people dont like arp stud kit because there are loads of stories about them them cracking the block

i used arp with no issues however, they MUST be installed correctly

it looks to me like you wanting to go for stage 3. so i would have standard compression, standard cams, t34, siemens 55lb injectors, rs500 intercooler, decent breather, chip to suit

in an ideal world a live map is best, but its not cheap, circa £500.