Since you have the GM 5/10 wheel bolt pattern, the first tubeless tires were put on tubeless rims with that bolt pattern. Many were put on farm trucks in the late '50's. It might be worth looking around for some of those tubeless rims, even if you can find a pair to start with.

Ed

'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.