3 Use a straight edge (flat steel ruler will do) then a feeler gauge to check straightness. (a torch or light can also be used on one side of the straight edge while looking on the other side of the straight edge to see if light is visible)
4 Gasket should be a proper Victa head gasket or equivalent gasket paper not home made paper gasket.
5 you can use Loctite 3JA Aviation Gasket Sealant non hardening on the head gasket.
6 Check top of cylinder with the straight edge.
7 A new stanley knife blade will remove an old gasket , if you use Loctite 3JA Aviation Gasket Sealant non hardening next time the gasket can be removed very easily .
8 Dummy fit the head on without the gasket ,nip the bolts up to make sure the bolt threads aren't bottoming before the head is flush with the cylinder ,sometimes people leave flat washers off head bolts or bolts are slightly too long or threads are rusted ,carboned damaged ,all contributing factors for the head not tensioning up correctly.
Sometimes a tap and die nut must be used to clean up the old threads.
9 Old spark plugs can misfire so a new plug is required to rule that problem out as a contributing factor for a blown gasket.
10 If the motor has points ,clean and gap them and reset the timing .
11 I would check your 4 crank case bolts aren't loose and the 4 lower cylinder bolts.
