C15 over compression

[Sammy mac]

Have just bought a 1959 ss80 c15 trials converson but compression is to great to kick it over when hot
Had a heath robson decrompressor fitted which i repaired the rocker box lever on but dissaster it lifted the rocker enough to let the push rod fall out so i would rather not have it
I dont know if a high compression piston has been fitted and know gaskets might compromise pushrod length
Anyone got suggestions please

[DON GRAY]

Engage gear, roll it backwards - clutch out turning engine over until it hits compression. Disengage gear & give a heafty kick. If everythings ok she'll burst into life.