Hi Boregy,
It sounds a bit like the 'bloke' may not fully have understood how to check compression on older Briggs engines, of the 'Easy-Spin Starting' era.
It's not fully explained in the current edition of the Briggs Repair Manual that covers these older engines, either - the P/No CE8069 one.
There is a scanned copy of the original hard copy Briggs Service Manual from that era available [free to subscribing members], in ODK's Briggs Manual Download section.
That is, with the cowling off, to spin the flywheel backwards, and see if there's sufficient compression for the flywheel to stop, then 'bounce' forwards slightly.
That said, it was also very common for the exhaust valve head to wear down, until it ran out of tappet clearance.
