One place I inquired with to install my gears indicated that they don't use a chip to recalibrate, they have some module that does it, could be the same thing.
To install the gears, your mechanic will have to remove the differential and bolt the new ring gear on. I know you said you aren't interested, but it is worth it to save up a bit longer and buy the t-lok also. and to install the gears for $150 is incredible. Most places will charge $150 for labor then you will need an install kit which includes new bearings, shims, friction modifier and that runs about $120. Just double check that your guy is going to provide the install kit as well.
Gears are the most expensive mod I've done, with the gears/t-lok/fordchip/install, It came to about $900 I think.
Remember though that the chip also modifies the rev limiter. If you fix the speedo, the computer is still looking at the RPM's in relation to the gear you are in, since you will be running higher RPM's, you will probably hit your limiter between 90-100mph I think.
the saying goes "there's never enough money to do it right the first time, but always enough money to do it again"
This is one important/noticable mod. It's worth it to save up and do it right, which IMO means the addition of the T-lok and fordchip
to your plans.