Stock Temp Gauge vs. Replacement Engine... Who will win? (Need an expert! :))

[jocko]

Ugh. Well, as I settle down to the final details of re-doing my interior, I'm starting to learn why the PO did some questionable things...

Here's my problem - PO had a hideous $5 aftermarket temp gauge bolted under the dash. I just assumed that he installed it because the old gauge stopped working. Maybe not the case. When I went to re-install my refurbished dash, I knew I needed to check the wiring and run the temp sender wiring through the normal instrument cluster harness (i.e. cia the circuit board). So, went about finding the discarded (i.e. hidden under the brake booster, out of sight) original temp sender wiring harness. That was good that I found it! Then, planned to swap in an original temp sender since the one in there was probably old, and more importantly, mated/calibrated to the aftermarket gauge. So, after wrestling with the silly spark plug shields so I can get to the sender to remove it, I get it out and find that the hole in the heads is MUCH smaller than the hole required to put the replacement TU5 72 Chev 350/stock heads temp sender in. So, while the anti-freeze is pouring all over the floor, I stuff the aftermarket one back in to stem the tide. Anyhoo...

So here I sit, trying to figure out how to solve this - I can't put a stock temp sensor in the heads of this replacement engine, don't want to try to stick it in the manifold intake manifold somewhere because that's "not quite right" and it will read high compared to in the head, and I want to use the stock gauge and not run an under-dash aftermarket one after all the work of restoring the interior.

Here's the engine data:
Current Engine stamping (actually, it's just a sturdy sticker): V0529P34 (can anyone pls point me to a reference of this engine - specs, etc? It was installed in 97 by PO's local dealer, but who knows what year engine it is or how long it sat on the shelf - it's just a stock replacement truck crate engine, but not a center-bolt valve cover type).
It was replaced in approx Sep 1997.

1st Pic shows the aftermarket sender in the head, 2nd pic shows the removed aftermarket sensor to the right of the correct stock one for a 72. I think. 3rd pic is why I want to do this - the resto'ed gauge cluster... I've heard folks on here state that the Wells TU5 (on the left) is the correct replacement sender for a 72 350 with stock heads, so that's what I got - and it looks like the correct one to me, if memory serves. Anyway. I've read several helpful threads on this (still pouring through this one, it's helpful, but haven't found the solution yet http://67-72chevytrucks.com/vboard/s...d.php?t=581719).

So, HOW do I run a stock in-dash temp gauge in a replacement ~1997 Goodwrench 350 with stock 97-ish heads that have the smaller diameter opening that won't fit the stock 72 sender)? Am pretty sure that the aftermarket sender won't work with the stock gauge because it uses different resistance ranges to drive the temp range on the aftermarket gauge. Appreciate your help.