Hi,
Thank you both for the replies and advice, much appreciated.
I have put some of your advice into practice and can now get the drum on and rotate it to a degree. I will continue to fine tune and get that extra mm to get it perfect.
The 60's drum has the same inner diameter as the split drum, very odd why one fitted better than the other. The drum shoes have original partially worn linings from the selection I have, all are approx 4mm thick.
The pins themselves are all of the same length unlike those in the Samba reference (could they be wrong!?!) - all pins that I have are from several different original standard backing plates. The actual shoe seats against the adjuster so the only way to get it to go a little further back would be to file the shoe edge where it meets the pin slot by a small amount - one option I may take as a last resort.
The only other thing that I'll need to do once I've sorted this out is to get some lug nut thread insert (time-sert?) put in as one of the drum hole bolt threadings has worn... Hopefully some garage can do this.
Thanks again, these old splits are definitely a labour of love!
Leon.