Chummy engine swap

[PeterN]

I have a 1930 AE fitted with a 1934 engine with a high compression head and a 4 speed gearbox. The existing engine block is number M233185. This block is ok but it had a crack in the usual place , which I managed to repair, and it's very worn in the valve guides. 
I have another block (M236165) which has been leak tested and is fine, but it needs some work. 
Before I go ahead with this can I check anywhere if the M236165 block will fit as a direct replacement.

As a bit of a purist I'd rather replace the existing engine and gearbox with period correct ones but that unfortunately is financially beyond me currently (even if I could find said engine and gearbox)

I hope that all makes sense. I'm grateful to listen to all comments

[Chris KC]

As far as I know Peter, all blocks are interchangeable.

Depending on the condition of the faces, you may yet find that your "new" block is also cracked once it's cleaned up.

Personally I would never skim a block if I can get away with gently lapping it on a surface plate. They are slowly getting smaller and smaller and this has knock-on effects for pistons etc.

Is your '34 crankcase a "high frame" or "low frame" type? Off the cuff (I could be wrong) I think both were made in that year.
There's about 5/16" difference to the height at which it sits in the frame, which can result in fouls (if anything this might work in your favour).

Finally, I let it be known at Beaulieu one year that I was looking for a circa-May '34 crankcase (to build up a "correct" engine for my RP) and within 10 minutes I'd found one within a month of my car's build, for a modest 40 quid. So don't give up too easily.