Have 'built' the redneck versions before when needed, but will build a real unit soon.
Saw a nice 'foldable' unit a SEMA that I took some pics of. They might give you some ideas.
Pics show the upright unit with an engine on it & a folded one next to it on the ground. Unit was adjustable for any standard BBF, BBC, SBF, SBC, although it could work for most any V8, at least.
Don't have the info in front of me, but it was about $1k, complete with fuel tank, rad, overflow tank, gauges, etc. You provide engine & battery.