"Pectel P8 engine loom" doesn't mean a lot unfortunately (the loom could have been made for lots of different specs) , but I'll try to help.

If the loom is for a 4x4 head, then the sender location for the temp gauge is towards the rear of the head on the inlet side, as opposed to the front of the head on the turbo side of the 2wd head. Perhaps the wire is in the loom and simply needs to be extended. Standard wire colour is brown/white.

The rev counter wire is usually in the engine loom, and feeds to the gauge via the 9-way multiplug that connects the engine and car looms. The wire is green, and takes a feed straight from the ignition coil to the multiplug. Check that there is continuity between the coil and the multiplug, and that the multiplug has the connectors in the right place. If the engine has been converted to run a coil pack instead of the original coil, or escort small turbo coil packs, then a mod will be required to the clocks.

A Pectel monitor can be used with any loom if the appropriate connections are made (total of 4 wires are required) and the chip in the ECU has the Pectel coms enabled - talk to the person who wrote the chip to find out if this is the case.

A SECS monitor can be connected to the loom - it simply piggybacks the standard sensors. Access to the ECU loom connector will be required to add additional wires.