out of an a15, 110hp should be easily available with an almost stock engine, just efi, elec dizzy, slight cam and thats about all. extractors and an exhaust.

on the way to danats, one of lags mates had a 1200ute with a12 on lpg, when his 200,000km plus a12 had direct lpg injection it made more than 120hp, but a bit less with just a normal mixer inlet.

From this, you should easily reach your target.