Couple things:
Drilling the thermostat is NOT an acceptable alternative to the external bypass. Will it work? Yes, maybe, sorta. Will your heads still be at risk of overheating and cracking? Yes. Will it keep the thermostat from regulating engine temperature properly? Yes, in both directions. When the thermostat is closed, the heads will run hotter at the double exhaust valves than they should because not enough circulation within the block, AND the overall engine temp will not come up to proper operating temp because the radiator is partially in-circuit when it shouldn't be, costing you mileage, performance, and increased engine wear.
This unit actually works.
http://www.harborfreight.com/non-con...ing-61894.html You can use it to measure the temp of the thermostat housing to read engine temp. You can also use it to read the inlet nipple on the radiator, to see if your thermostat is opening at the proper temp. The thermostat nipple will run about 140* until the thermostat opens, and then jump to about 195*. That is, assuming you do the coolant bypass correctly and don't half-ass it by drilling the thermostat.