If you get a TMXR chassis and bones then I doubt you'll have an issue with the uprights; Phil is well aware of the issue and supplies wishbones which have a cranked leading arm to clear the rack for people building a book chassis.
I guessed you were in the UK, but it's still a pretty big place
I have a new and unused MX-5 specific tank for sale
the sender/pump assembly will need modifying, but I think that's covered on the forum. Failing that, there are a number of people who will make a tank to your requirements, for example K4KEV on here did/does tanks (the tank I have for sale is one of his).