SU Carbs.....
Ok, here's a little story.
I lived for many years in The Netherlands (Holland) and they have been using LPG for donkeys years. One of the biggest problems with the old installations (pre-1990's) was that people used LPG as their primary fuel and petrol as a reserve. The car was started and run on LPG and, like I said, only switched to petrol when they were out of gas.
This resulted in the carbs running without any lubrication (Petrol) and, in the case of SU (or similar) carbs, means that the needle and jet wear excessively resulting in a very rich mix when they are eventually used on petrol. It doesn't take much to wear them out. In my case I hadn't needed to use petrol for almost six months, and when I did, you could see the needle on the petrol gauge going down (almost).
Anyhow, newer LPG systems (from the mid 90's) now start the car on petrol and switch over to gas automatically so the carbs and there parts get lubricated. At least the systems in Holland do. Never had LPG here in the UK.
If the if the SU carbs you have are similar to the ones used in the original Mini's (showing my age here) then they are easy to strip and clean. Parts are cheap and it's a fairly simple process to do it yourself. The ones I have seen on all the project threads certainly look similar so you should not have a problem.
Lovely carb. Very simple design. Very reliable. Easy to adjust.
Hope this helps.
Vic.