The rear ends were standard 5.38 ratio. How much wider is the Blazer rear end? So, now do you carry two spares?

I exchanged the steering gear in my Jeep with a Hudson steering gear, worked great, they are hard to find now. Today, a Saginaw non-power steering works well. Check out a modern Jeep.

There were/are 11" drum brake kits which are much better than the original 9" brakes.

You could get a Dana 44 front axle(others will work too) and put Blazer front spindles on the 44 to match your rear bolt pattern.

Good luck.

'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.