If that sort of thing gets the juces flowing.. then i'd suggest buying an antique tractor or a chinese tractor.. both require a bit of hands on 'greasy finger' kinda touching to keep them running... of course.. you figure the antique needs it since it's decades old... and i guess the excuse for the chinese is it's cheap.. er.. inexpensive..
I came across 2 units this spring just like you mentioned. The owner of the lot I was cleaning up tols me I could have one if I could help get his on the back of his tractor. I had an old 12 inch pulley and shaft from a combine and I put a set of pillow block bearings on it. Then on the end of the shaft I adapted a universal off a pto shaft to his tractor. There was an old 3 point carry all there and we mounted the chipper there. It really hums about 2 inches soft wood and 1.5 on hard wood limbs. The tractor just idles and hums along. The set up isnt quite clean as I like but it suits him. The previous owner left them there as the engines were too much to keep up for 2 or 3 times a year useage. Mark has used his to chip shrubs and such around his over grown place. I ve moved about 10 yards of chips from his machine. Im wanting to try to get to mine togeth this month.
Well... I ended up buying an edger with a B&S engine at a flea market for $25 and swapped the engine into the chipper. It was too easy & too cheap to pass up.
My next hair-brained idea... pto powered grain mill (for domestic use).