late 70's C50 engine options?

[QldRtv]

I'm looking at buying a C50 a friend has had for years but has now retired (he was still working it a couple of days a week when he was 80!)

Now, I *think* its a 78, but I'm not 100% on that, I do know that its a 292 with a 4 speed and single speed rear, the box was the same as the one he had in a C20 except the C50 had a drum type park brake bolted to the back of the box (helped him pull the box maybe 12 years ago when it broke the input shaft sleeve)

I'm a couple of thousand miles away from home at the moment so I cant really duck around the corner and ask him for more information, but if we can agree on a mutually agreeable price, I'd be sorely tempted....

The thing for me is I'm not incredibly interested in the 292 and I would like to drop something like a 6v53 or a 6v71 into it, or maybe even a V8 Detroit if one will fit. A later 6.5L diesel V8 isnt out of the question either, but I'd prefer the Detroit......

The problem is, in Australia the powers that be arent incredibly happy with engine conversions other than factory options, so I was hoping if anyone could tell me what engine options were available in that era?