Installing temp guage sensor(aftermarket)

Thanks, cudamark. 45lbs oil pressure going down the road, 10-20 at slow idle. I replaced the t-stat as part of my initial thorough tune-up soon after I bought the car. Made no difference and the old one looked pretty new. I considered going to a hotter one, but didn't think that was the answer. Seriously, when I first crank the car it runs good for a forty yr old engine that I suspect has never been rebuilt. I can go thirty miles and it'll run fine. I stop and go in a store 15 - 20 min, come back and temp reads 170, it's hard to crank and clatters like hell climbing a hill.
Tomorrow I'll try to pull the cluster and check it out. If I can't get the temp to work I'll probably wind up drilling the head. The new temp works, it's just that I had to fit a tiny nipple in the orig sensor hole, then use fittings to basically make an external chamber for the new sensor to set in. Didn't seem very efficient to me. I just wasn't sure about drilling the hole. The idea had occured to me but I was scared that might be a drastic solution and experience has taught me that if I'm not sure, then I shouldn't go doing anything stupid.