Engine Health - 235

[FAKKY]

57 Panel truck
Had a guy and his dad come by today to look at my 235 engine im selling. Long story short said it was a clean/nice looking engine but was "worried about a lifter "tick" that probably meant it needs rebuild"....

I hear the same tick but honestly just felt it was at worst needing a small adjustment. Not sure how someone determines a rebuild required from just a lifter tick - but not too familiar with these engines. So best way to determine engine health ?

Was planning to just

1) Adjust lifter/rockers with engine running until goes rough, then adjust back until quiet and smooth and go 1/2 turn.

2) Run a leakdown test.

3) Compression test.

Thoughts ?
Also not even opened the valve cover on these engines - what size spark plug for comrpession adapters - 14mm like a modern engine or something else ?

thanks