Thanks for all the replys. Regarding mech vs hyd, I guess it will depend on clearance & engine to frame location. If I can make mechanical linkage work with a Z bar or a '55 Chev arrangement as Desoto suggested, I will go with that. If not, Centerline's hyd system is very nice & uses factory parts (except for the pedals) BTW, I did find a set of pedals on ebay which were designed for the '61 3/4 ton master cyl & clutch slave cyl
Tardel pedals (ebay)
Here are the Napa p/n's if anyone is interested...
'61 Chev 3/4 ton PU brake mstr cyl, NMCP34404
'61 Chev 3/4 ton PU clutch slave cyl, NCF73466
However, it is a single pot system as Centerline pointed out, unlike a modern dual res brake system which divides the front brakes from the rear. This system lacks that safety feature, but that's what the e-brake is for, right?
Autogear, will let you know how the adapter works out. It is a very nice casting.