3 bearing engine

[Ladybird]

We have owned our 1936 Opal for just over a year, have had a lot of fun despite covid and have covered more than 1,000 local miles.  We have sorted most small niggles including a top end rebuild, however there is a persistent bottom end rumble when the oil warms up and major work is needed during the winter. Past experience suggests that engine removal, dismantling, delay awaiting new parts and the probable discovery of a cracked crankshaft could lead to the car being off the road for some weeks or months, something we are keen to avoid.  We are based in Somerset.  My question is; does anybody relatively local to us have a spare 3 bearing engine under the bench that we can borrow to swap in and keep the car running while we rebuild ours??  Obviously we are happy to indemnify the owner for wear, loss damage etc...  Can anybody help??