Brad,

Nice truck. The original engine bay will hold a GMC 302 6 cyl. engine in place of the 228 or whatever is in there now, provide plenty of power. Engine displacement displayed as initial numbers of engine SN, i. e. 302xxxx, stamped on right side near starter. A more modern 292 Chevy 6 will also fit in there lengthwise with only a relocated right engine mount. Update with a modern 4 or 5 speed trans.

Since it was a fire truck, it might already have thicker radiator, although 5 psi max. You can put modern axles, with modern brakes and power steering under that frame. Be aware that the front axle is narrower than the rear axle. Wide front fenders, while rare, do exist.

Another option, as mentioned above, would be to put the tin only, on modern running gear, front fenders, still narrower.

Good luck.

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.