First off, welcome to the forum! There are lots of very knowledgeable folks here who can help with pretty much anything you face!
As someone who purchased a Disco with pinned liners, I do not recommend pinning them. It's a hack fix at best. The block wall is so thin that there's nearly no thread engagement possible for the pins. The guy that did mine installed pins that were too long which fouled the piston skirts and destroyed all the pistons, not to mention put a bunch of metal in the motor. The pins eventually fall out which causes a MASSIVE oil leak and the liners will bang all over again. Additionally, there's no good way to ensure that the liner is "topped out" in the cylinder when you pin it which can lead to frequent head gasket failure. Overall it's not a good solution. It looks like your engine is already out - go do some lifeguarding and start an LS swap!
This is a great vehicle to learn to wrench on for sure and they're tons of fun to drive.