I’ve built a few.

My current one is Focus Rs based and good for a reliable 350 bhp +

low miles Blacktop. £250
Rs pistons £300
forged rods with Arp bolts £350+
Piper valve springs £200
Gaskets, bolts, bearings, seals £250
Machine work £100

built by my self.

Inlet full Rs with 440cc Injectors. Rs bits are now very hard to find.
Exhaust manifold. I’ve made my own.
Turbo I’ve got differant ones.

Clutch is FRs Ap racing.

Engine managment, I do things differently here again it’s Focus Rs.