H22A8 is OBD2, P13 OBD1 <-Solution: harness conversion
BUT
IAC is different. I think the Euro R is using 3-wire and P13 ecu only accomodates 2-wire.
Euro R VTS does not have the oil pressure switch if I am not wrong. P13 ecu will certainly flick a CEL 22 for missing oil pressure switch. Check your H22A8 VTS for oil pressure switch.
Get a P5P ecu. If not available used, get a new one from the dealership for about 800-1100 bucks. Stock rev limit for the P5P should be in the mid to high 8Ks.