mechanical speedo to electronic conversion

[dusterbd13]

i know you guys have probably done this, so ill ask....
i want to use a transmission that only has the option for a VSS output. i want to retain the factory gauges in my 64 chevelle cluster. it has a round speedo with a 270-ish degree sweep.
my thought is, that i shouldnt be too hard to swap in the guts of an electronic speedo to the mechanical gauge. what do you guys say? my thoughts are leaning towards an 80's-90's gm speedo, cut the guts out, mount the guts to a cannablized chevelle speedo, add the right needle, and rock on. probably have to do some pulse tweaking in the PCM for calibration purposes (running GM EFI from a 84 TBI truck, plans call for 4l80e from a 94 as well).
anyone have experience with this? anyone have a link to something similar? how to's? how not to's?
thanks
michael

[408sbfmustang]

you can just use a Cable x