Howdy, I'm just new here (yesterday) but am going after the same thing with my '73 T-100-D. The Hagstrom adjusto-matic metal bridge on my '67 Hag Viking is an exact fit on the old wooden bridge thumb wheel posts (75 mm center-to-center) but there is a height shortage, esp. if you want full contact between the wooden base and the metal bridge. Still working on finding another Hag unit (was one on eBay last week but I missed it - BIN $65.) Heck, I might try a Bigsby B6 conversion anyway which will change the kind of bridge I use. Bigsby makes a gold or chrome "rocker bridge" that pivots back & forth; it's also compensated for wound "g" string however. Elderley has 'em, Stew-Mac too I think.
Oh yeah, if you look for an old Hag bridge, they made two kinds: one with indents underneath to sit on the thumbwheel bolts, the other with holes that the bolts can fit through. You want the latter kind; lets you adjust the height more.
My T-100 had a previous major neck repair (4 screws right through the wood, filler putty on top!!!) It's ugly but only from the back side. That neck ain't goin' nowhere. Anyhow, if it were mint I wouldn't do the Bigsby but for $475 last summer I've found my dream live axe; puts to shame most Gibby 335s I've played, both in comfort and tone, love them HB-1 'buckers!
Good Luck!
firestarter
1973 T-100-D-BLD
1974 D-50-NT
1976 D-35-NT
1984 F-42-NT
1988 FJ-30-12 BLD
(and....
1940 Martin 00-17
1950 Martin 00-18
1967 Martin 000-28 Braz.
1975 Martin D-35
2003 Larrivee LO3 R
various electrics & basses
yeah, I know, get a life...)
(or maybe a dark colored Guild)