B3Guy said:
...back to the original q: is it workable?
It can be done, but it's just not practical. You'd have to rout the top, thereby wrecking your "vintage vibe" and possibly the finish as well. Then, in order to take advantage of the increased travel the recess would make available, you'd have to substantially open up the sustain block opening, requiring more routing from the rear. Otherwise, you wouldn't get any increased range of motion anyway. Finally, the pivots on a vintage Strat vibrato bridge aren't designed for that range of motion, so you'd have repeatability problems. That is, the bridge may not return to neutral reliably, and the pivot points may wear prematurely.
So, I'd strongly recommend against the whole idea. You won't really gain anything, and you're liable to lose a lot, this on top of already using a less-than-ideal design bridge in the first place.
Besides, listen to some old Deep Purple, such as "Highway Star". Ritchie Blackmore is playing a "vintage" Strat back 100 years ago before it was considered "vintage" - it was a
new Strat. But, it had the crummy 6 point limited travel trem, yet you'll hear some really wild vibrato going on. Thing is, a lot of that was in his
left hand. Guy could
wank on a guitar neck. Still, he beat the hell out of that bridge as well, torturing out some real stretchy stuff. Jimi Hendrix, from the same era, was doing the same thing the same way using the same gear. Mssrs. Floyd and Rose were but twinkles in their daddy's eyes back then, so Ritchie and Jimi had to get most of their vibrato the old fashioned way: they played it left hand. The wang bar was mostly just for special effects diving.