I'm running this combo through a th350 with 43. I really like the final ratio. I'm running a pretty low stall around 2200 though.
I can crawl stuff with yota cab trucks or smoke the tires on a big ledge into second gear.
Are you still running a single mixer? Any more details on the motor? What are the spec on the cam?
Yeah still running single mixer. Standard bore 350. Nothing really fancy it's got world product heads and a cam that I believe is just off the shelf. I called comp cams to see what they would...
My sbc on single propane was a good running engine to begin with but wasn't making the kinda power I wanted. So I pulled it down put in higher compression pistons did some machine work to my world products heads got the ratio somewhere to 13/1. Put in a good cam for the propane now it will smoke...
But.. If you are happy with what the ford was doing and the 350 is going to require a rebuild and is going to require time to fab it in there and buy a propane kit. Might make more sense to just rebuild the ford
Propane isn't bad except the obvious. A new oil pump probably won't do you a bit of good in the ford. I'd say build the 350 with a lot of compression with a matched cam and go have some fun. This is what I've got and I'm pretty dang happy with it