jeezealou, thats the truck to start with. I just shortened an ext cab the other day for a swap, its easy peasy. took about 2.5 hours start to finish, and the nice things about using an ext cab chassis are:
1. they are easier to find than reg cab long beds
2. when you shorten them you can get the 116 wheelbase and not have abnormal bed/cab gaps or uncentered wheels.
3. you dont have to cut that stupid bumtangle rear cab/front bed mount off the frame
4. you keep all 8 bed mounts AND the spare tire still fits behind the axle, with a rclb you only have 4, the front one is on that bumtangle and the rear one gets cut off and the spare doesnt fit.
you can use the shortbed of the ext cab as the bed floor, if you cut the front wall ~3" high and bend it down and shorten the width to ~51", gives you tubs and a strong steel bed floor with 8 bolts in about 2 hours start to finish.
sorry to gush. if there is any combination of frame or cab or bed length, I have done it
mr48, pick up an s10 and I will send you some 5.25" tall mounts (flat cab floor, no air director trimming, no loss of bed depth.