If you want to keep your Granny first gear then a T5 wouldn't be the transmission for you. However, if you want to be able to cruise at highway speeds and take advantage of the 216/235's torque band without turning up a bunch of revs, the T5 is a viable option. The T5 I'm using is from an S10, a non-world class box that is available for $150-300.00 and has the shifter located forward....about 6" to the rear of the stock sm420 shifter and still in front of the stock bench seat. Inexpensive and relatively simple to install in an AD truck and it makes for some fun driving!
The hybrid T5 you mentioned from behind the 305, using the S10 tailshaft, has a closer gear spread and I'll let you know how long it lasts behind a 355. I've run the FoMoCo version behind a 345 HP SBF with no problems. My new project vehicle is also set up as a cruiser so I'm not planning on much if any abuse. The shifter location is 6" forward of the front seat edge just as it is in the AD truck.
As for the price comparison, you must have some inside pricing on the GV unit.....for that kind of jingle I could just spring for a T56 and have it done with!! I don't think you'll find a transmission out there that is any tougher than the Sm420. So if you intend to use your truck as a truck, the GV unit should open up a whole new realm of possibilities. Might be kinda fun slipping it into 8th gear.........
Dave
