I will be doing the seatbelts with a plate inside the pillar, when you have a look at the bolt head on the outside of a pillar, I have very little confidence it would hold my 127kgs
The FE already has the holes on the inside pillars and I can get the approved plates pre-made from an auto trimmer in Adelaide. Although I believe the new Klippan Seatbelts come with the all the hardware.
The motor I am using was originally intended to be a gas-only motor. Hardened valve seats are your first stop, and I understand a boost in compression is good, although not entirely necessary. Timing will be a little different, but apart from that it is just a normal motor.