Try Pumabuild mate, they have fitted FRS engines in all manner of things like Pumas and Fiesta's.
I know it's not an ST170 lump, but cost wise it 'may' be a more effective option as they provide a drive in drive out service.
If you wanna stick with the ST lump, your gonna want to spak to someone like Ian at Area6, or I 'think' Power Engineering have done a turbo ST engine... With that engine you're gonna have to have to bin the VVT the inlet manifold, obviously you'll need different pistons (forged low comp) and an aftermarket ECU...
Actually, also try Jamie at Jamsport, i'm 99% certain they are putting an ST lump in the Blue Jamsport car, and they are main dealers for 2 o 3 different aftermarket ECU's.
Hope that helps
