I've rebuilt a few of the Penta engines. Rings and bearings are all the same, just be sure you get the correct rod bearings if you have an eight bolt crankshaft.
Gasket sets are different because of the o-rings Penta liked to use.
Biggest thing is to rebuild the raw water pump and be sure that its seals are perfect. If it lets go raw water will enter the sump through the timing cover. If in doubt replace the pump ($).
Otherwise simple and easy.