Is it worth LPG'ing?

I've got an 85 RRC on twin Strombergs so regarding LPG kits i guess i'm stuck with a single point system.

Are these any good/worth investing in?

i have single point and its fine, it does backfire now and then but generally its good.

Only you can answer that question depending on how much you use it and how many miles you go. (and how much cash you have!)
LPG kit on a carb engine will be pretty cheap to buy, either new or second hand.
Either fit yourself and get it certified or get them to do the work.
Will work out cheaper than a diesel to run if its well set up.

Money wise it makes complete sense, no doubt about that.

I'm concerned about how well it will run. At the moment its brilliant and i dont want to fit a system that will create me problems and take the enjoyment away from that lovely V8.