Hi Super55 ,I found a 1"1/4 bore MC this is the one I used on my 1948 2 ton
http://www.rockauto.com/en/moreinfo.php?pk=309636&cc=1052086&jsn=567&jsn=567

http://www.ebay.com/itm/Raybestos-MC39324-New-Master-Brake-Cylinder-/111878603876?hash=item1a0c7c0464:m:mRyd-vVY1EaAV0w2SkkAt2A&vxp=mtr

1"1/4 bore is the same as the original MC so it works well with stock brakes .
with a 8" dual diaphragm booster ,Pirate Jacks in NC is where I found one http://piratejack.net/ .The only problem I have is it runs out of vacuum so it needs a vacuum tank and check valve put on it .1st hit on the brakes it's great then it gets hard .You can find a tank on a truck with air brakes or older school buses that had juice brakes . I have a least 6,000 miles on on my conversion .Mine is still mounted under the floor .PM me your phone # and I can give you more details . Paul
Dorman has the same http://www.ebay.com/itm/Dorman-M39324-New-Master-Brake-Cylinder-/152032000320?hash=item2365d03940:m:mXT3BXtl87kjUMulJGbm2tA&vxp=mtr

Last edited by PAUL NOLZ; 03/31/2016 1:44 PM.

1948 Chevy 2 ton flatbed ex fire truck , and various motorcycles .