I got the answer to the disk bolts, they are 3/8 BSF - so thats another type of fastner on the car, UNF, UNC and now BSF, still a quick trip to my local Fastner specialist in Coventry yielded some 3/8 BSF Cap heads, and on go the disks to the hubs
That done it was time to try and get the front diff onto the engine while its upside down, It fits, but what a close fit, I had a rag between it and the sump to protect the paint, but had to remove it to get it to line up. No wonder those 2 sump bolts had been ground flat, all I need now is the diff sump cover back, and I can then "right" the engine and fit the timing chains and cover.
I need the rear diff now, and the replacement oil seals for the front hubs, and all the suspension will be complete.
653 hours worked now, 3 tonight.