Stop buying off the rack dress shirts and start buying custom shirts from Hong Kong tailors. I think you can get them for as little as $40 from Jantzen if you don’t mind waiting forever, and there are plenty of places that have offerings in the $60 range (with more expensive options if you want fancier cloth). Many of them do tours of the US where you can get measured by them and ask questions if you’re wary of ordering custom clothes based on your own input.

Lands End also has a custom clothing options but its a little more expensive and you have to send them your measurements.

I have some banana republic t-shirts that fit okay, though as i’ve washed them more it seems like they’re getting a little too short.

There’s not too many options, though you’re still within the outer ranges of what a lot of places will carry. As Captain Haddock suggested, you should look at Eddie Bauer and Lands end (lands end also has custom pants options). I don’t really like anything I’ve received from JC Penney (too Big and not as Tall as I’d like).

I’m even out of the range of a lot of the tall offerings from these places.
shirts: 17.5 x 39.5
pants: 38 x 38 (actually more of a 37 inseam, but finding pants in odd sizes is kind of rare)
chest: 46xl

There’s also King Size. I think they may be more focused on the big aspect, but I have a bathrobe from them that’s pretty awesome. And I recently received a catalog from a company I’ve never heard of that looked to be more Rochester Clothing like, but I think I threw away the catalog and now can’t remember their name.

36 seems like the limit a lot of places will sell, but if they run a little bit long I can probably wear it.