i just got me a 30k focus rs bottom end for £300 now i need a head but will a blacktop head be ok?

i have the cams from the same engine so all i need is a rocker cover and a head to make it compleate

all i know it the valves are made different. so maybe get some new valves for a blacktop head?

the chap i got the engine from says a rs head is worth around £400 and sujested that i fit a st170 head and block off the oil pressure for the vairable valve timing and fir the rs cams in that

so what do you think?