Yo Freddie. Propane Gas is what is used most with these type conversions. I see many people term "LPG" in their posts, but when you read through...turns out it's regular propane. I'm still not %100 on what LPG is or means.
LPG is a generic term and covers all liqufiable petroleum gases. Low grade propane, (BBQ), may not be as as pure as the auto standard HD-5.
Any Details on the system you narrowed too? looks like twin Impco 425 mixers & twin regulators is required from my research. Either a custom Side mount mixer to turbo compressor manifold, or a hole in the hood.
The simple reply is that it's all bolted on. All that is needed is one CT425 mixer, (in place of the carb), with an adapter bolted onto a Q-jet throttle plate. The other necessities are a lock-off, a vaporizer and a converter. All easily fit in the engine bay. I haven't measured it's total height yet but if it's too tall I may have to make the bulged hood functional. The project is temporally on hold, (still searching for a tank).