There's a few ways to do a tach...
I used the service feed on my distributor cap.. but of course that's for an old 3SFE motor. I have no clue about the Rolla engines.
Oil pressure is a bit more diffcult, but now by much. Depending on whether you get electric sender, or mechanical gauge. Electric sender you'll just need to put a new T-Fitting where your stock sender is, and then put both on there. Then run the wire to your gauge. As for mechanical... you'll have to run a capillary tube into your cabin through the firewall.
Ammeters are easy... I think. Just hooking up a 10 gauge wire to the Alternator or something like that... Not quite sure. But all it is is simple wiring
Hope that helps. Wait for another Rolla member to help with Tach sending info, and oil pressure fine points.
All can be done yourself... just take your time

Also do a search to find some more info.
Good luck.