Gidday Col, welcome along, I won't give any 'good' advice, save to say that I have a ~circa 52 plunger, with RR alloy head and barrels, LJ crank, so bits fit but need careful attention to detail, and it's not always apparent till you get to it(that is to say they may 'look' the same, but...?are they?).
You'll find lots of answers and help if you get stuck
cheers, duTch
Edit If there's no picture here, I've removed it 'cos it's in the wrong place