just shooting in the wind here:
might take a good hot battery with you.
tools to take plugs out
shoot some 30 weight oil in each plug hole.
use a compression checker and check the health of each cylinder.
about all I would know to do,
I have forgotten what psi you should have in this motor, something around 125-135 psi
if you have one reading 60-70 psi you know you have problems.
others know much more about this than I do,
they will kick in and give you good advice, all my advice will do in get you in trouble and is worth what you paid for it.