T5 swap to a 225 Slant 6?

That would be super easy for a GOOD machine shop to make All you will need is an adapter plate to adapt the trans to the slant bellhousing and a crank adapter to space the flywheel back the same thickness as the bellhousing adapter. If you know someone who is a good wood worker you could get them to make templates from wood and then get the machine shop to copy in steel.