i know they share the same gearbox which will be handy
GA14 gearbox and driveshafts are different to GA16 ones.
If you plan on modifying the 14 then just drop an SR in. Conversions are pretty cheap.....like really cheap. Would cost the same to modify the GA as it would to go 2 litre.
Price depends where you go. Main cost is usually the engine and associated parts.