the only way to get a rhd with no bodywork issues [ or minimal ] is a South african or an OZ bus.
Both are quite expensive to import from [shipping costs] , SA buses tend to get really really used, although we have a few very straight examples on here from SA. Oz buses are not as common in the UK, not sure why...probably the shipping and the fact they are not super cheap.
So most including myself have opted for LHD from the states, mine isn't rust free, but the rust that is there is easily fixable and I'm doing the first repair, most UK buses will be quite well gone rust wise or been patched multiple times.
For £7-8K you could import a US bus, and then have some money to convert to RHD if it really was a pain, most will say you musn't convert, but you'd get a pretty decent bus, and the resale wouldn't be too hampered because it'd been converted as the fact it's body would be in good nick, would outweigh the fact the bus wasn't as factory - if that makes sense?
This was my reasoning and tbh LHD is fine, the 'passenger' mirror does need to be on and setup correctly as in my Westy the rear wardrobe does create a blindspot, but the LHD in my mind creates a slight trepidation and therefore you are a better driver, and not complacent as we can be in our modern euroboxes......
I'd also buy the one with the best paint you can as repainting is very expensive in comparison to spannering new bits, also unless it is your hearts desire but a 69 onwards as I have found the '68 - one year only part curse' to be a little off putting at times and makes finding parts more tricky and more expensive in general, and the average punter wouldn't know a 68 only dash or clocks or westy top or...... :lol: