Rover T series turbo bottom end - overhaul?

[mercedade]

In my long-neglected 820 Vitesse thread, I'm about 9 months behind, but in the present day, I've got a quandry.

It came off the road with HGF (powersteering pump failed, which meant the keyed drive for the water pump failed...HOT)

In the time I owned it, it's always been tough to start when hot (as in, needs foot to the floor when cranking,  but always runs perfectly when hot).

After the head was skimmed and refitted, it was horrible to start and, when slightly warm ran like a sack of shite. A compression test found 2 outer cylinders to be dreadful and the inners two only slightly better. Theories ranged from still-banana shaped head, shot piston rings, or unseated valves in a scrap head that went fully bent.

I have picked up a NA 2 litre T series (oil tight - a fucking miracle) engine, intending to use the whole thing if possible, or just the head if not.

However, from what I can find online (which, let me tell you, is nothing like as easy as it was when rovertech.net was still a thing), the turbo bottom end is (understandably) different, so I'm left with:

a) use 'old' bottom end, with the 'new' head, using the old cams (or moving the cam sprockets across)

b) use both new top and bottom ends, but rebuild with new turbo pistons.

I favour option A, but need to know that the bottom end is good. So, my question now is - how can I tell? With the head off, there's a small amount of movement of the pistons inside the cylinders, but that appears to be normal - how can I find out if it's too much?

I'm after brains here - I've spent mine...

 

[mercedade]

I think I might end up trusting that the bottom end is good.

Does that seem silly? How can I check if the previous poor cranking was down to rings, for example?