I wouldn't buy the G-85 on ebay- if there's something wrong with it you could be screwed ( I've not had the best luck with parts these days) plus it sounds to cheap- the last one I bought was 228.00 in Dec '08.
Any forklift dealer in your area should be able to supply this part- no matter what brand they sell. If you have a issue e-mail me & I'll point you in the right direction.
As far as the primer button- even if the one you buy doesn't have one you can swap over the one on yours- no big deal.
As far as mounting- make sure you hard mount it- don't let it hang by wires or hosing, lpg is EXTREMELY flammable- it's around 110 octane & ready to light up. Propane can even self ignite from static electricity- I learned this one the hard way. Keep all hosing as far away from heat sources as possible. Do not mount the regulator to the exhaust- maybe close to it, but not touching.
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.