i currently run a 230bhp c1j r5gtt and my god does it shift more power to come this year as well

1.7 conversion isnt a bad idea if you want efi but there isnt much out there in the form of tuning, also the standard ecu is limited to about 12psi iirc, the standard cam is terrible for performance but there are cams out there which improve this no end.

there is efo conversions out there and it can be done for around £1200-1500 all in, but the route im going down is mappable ignition this gets rid of the standard aei unit and improves low down performance no end gains of 30-65lb/ft are had between 3-4k which helps improve spool etc

id personally stick with the c1j and join up to www.rtoc.org ,im an area rep on there and i can honestly say its a cracking club so much help on there. The big reason these got a bad rep are because numpties used just whack the boost up and not alter the fuelling and obviously they went pop. No group A carbs or massive main jets though thats old hat tuning and they run like a bag of shite on them.
i currently run 23-24psi through mine with no probs and my mates old one ran 28psi for 2.5 years and it was used hard