Thanks for the rapid follow-up. I have set of alloy push rods, so can measure to give me some idea (I assume it had been running given the oil and dirt that was covering everything in sight.) The 5th (now extra stud) clears the barrel and initially confused me somewhat as to why it was there.
Thanks for the tips on the rocker studs, the ones I removed were packed with washers and in once case an extra nut to get them to tighten. So a new set is required.
I have a piston with rings and there appears to be no barrel wear, only issue was the small end tolerances. A new one on the list.
The exhaust systems was one of the many, items missing. So will be on the look out for an early push one now.
Joining the club was the first I did and so far the archive documentation has been extremely useful. Once I have a better list of bits, I'll certainly be troubling the clubs 'Singles spares' man