i know what the head facing tool is. and, yeah, i was afraid i'd really need something like that to do this right. i was wondering maybe a flat file and gauging my work with a digital caliper around the circumference using the opposite/untouched facing to continually maintain evenness, if that makes sense. and, maybe just stick to trimming at the top of the head tube?
but, how hard is this tubing to hand file? i took a half round file to the underside of a unicrown fork to make a few mm's of tire clearance. i took off that "excess" under the crown you often see on the underside of the steerer. took about ten/fifteen minutes maybe

i have a picture of the frame in question in my email. i should be able to figure out how to get to the forum for illustration, but it'll have to wait until after work this evening

later. thanks for the replies!