Engine Temp Sender Adapter help

[huzilulu]

Hi Guys

I made it back home last night after an 18 hour flight... and was up at 2AM in the garage!! (Ok Ok I'm up because I am jet lagged, but still...)

I was able to get my hands on an adapter that has been recommended previously on PH to install a water/coolant temp sender into the LS engine block.. The sender is a Stack ST764 with a 1/8" NPT thread... the hole on the engine head is a M12X1.5 ... I picked up an Autometer 2277 adapter (M12X1.5 to 1/8" NPT) made for coolant gauges... now I have two problems:

1) The hole in the adapter is not large enough for the sender probe to fit through... Should I drill out the hole in the adapter and make it larger, or is it ok to slightly reduce the sender probe size (assuming its a solid piece - not sure how these senders work)

2) The size of the adapter is such that even IF the probe fits through the hole, the tip of the probe will only barely be exposed to the flowing coolant- is that sufficient area for the sender to work?

Thanks!