Checking head temp is cheap and easy.
The infrared thermometer was very cheap, but seems to be accurate enough.
However to get a comparison to check it by, I ordered a couple of thermocouples that mount under the plug washer, these are also cheap if willing to wait from China, although seem to be ridiculously over priced locally.
Once the motor is tuned and tested there is really no need to monitor the temp unless changes are made.
If your motor is too hot your likely to smell the oil burning off, but still good to be able to get a reasonably accurate reading.
My Soft tail had an angle fire head for a short time, and was getting a little hot, which was evident by the black stain to the underside of the piston crown.
If your going to try and get these motors to perform, throw away your angle fire head!