Ext to internal regulated alt wiring question

[RainFade]

OK I've got all the goodies for a serpentine conversion coming and have read the faq's and googled but have one silly question.
Can I use the gauge in my dash for the #1 wire from the new alt ?
I've seen it written up that you can wire to the idiot light or use a 35 -100 ohm 3 watt or larger resistor, then in another thread someone mentioned you could use the gauge in clusters so equipped.

My multimeter has decided to croak so unless santa brings me a new one I can't just measure the resistance of the gauge... and even then i'd feel better knowing others have used theirs successfully for extended periods.

I've got some 75 ohm 5 watt resistors but am unsure how well they'll hold up in an engine compartment even shrink tubed, tie wrapped and othewise protected.