There are specialised companies that offer engine re bore service with the engine in situ, normally the type of very large engines found in earth moving vehicles used in quarries. They claim to be able to rebore a block from 1-inch dia bore to 39-inch dia using laser alignment to ensure accuracy. Even if this was a practical and accurate way to rebore a Supra engine, there is still the problem of removing the sump to gain access to the crank and pistons which isn’t easy with the sub frame in the way. Then you would need to find a way to remove all the swalf and cast iron dust from the oil ways, some of which run from the front to the rear of the bock and are capped of with large hexagon headed grub screws concealed by the bell housing and front timing case back plate. The only way to do a re bore is as mrnickleye said remove every thing, this is my block ready for re bore I left some studs in simply because I had so many bits of engine parts lying around the house and garage, if I removed them it would only add to the problem of remembering which holes they went in. The shop that did the + .020 thou re bore charged ?90 GBP ( $176. ) and that included honing.