Loved my MK1 1.8 Zetec was RR'd at 145bhp with cams and supporting mods. Went OK for what it was and did high 20s around town and 40+ mpg on a good steady run. ST170s are decent cars for the money but personally wouldn't pay more than around £2-3k for one the market for these is real shit. Try find one which is fully loaded with heated Recaros and climate. Very reliable engines mine done 91,000 had no major issues at all and confident it would do 150k miles plus if I kept it and handle OK as well. Decent amount of poke for the size lottery if you get one producing 150bhp or 165bhp due to poor quality control in producing the head.