A Fender Bassman has been used for many years by many pro guitar players looking for that deeper tone that you are talking about. The SVT, if memory serves correctly, has a pretty large output transformer with pretty heavy windings inside. The larger the wire inside the transformer is, the deeper the tone. A perfect example of this is my homebuilt firefly amp. With the Hammond 125A transformer that the original schematic called for the sound was quite bright and less than stellar for my style of playing. I changed out the output transformer to a 125D (which is rated for higher power with very similar specs) and the bottom end filled in quite nicely. There's no more sound volume with the "D" versus the "A" but the "D" is much beefier with heavier windings to support the higher potential output power.

While this works for guitarists plugging into bass amps, plugging a bass into a guitar amp is a much faster track to a dead guitar amp for the reasons that teemuk has already described.

I just found this board and quite glad I did!

I've built both the DR Boogey and the JCM800 emus about a year or so ago. Both are outstanding as far as tone, but like what RDV discusses, the DR has quite a bit of noise in the circuit that I really can't tame much. What I did find, however, is that using (20 turn) multi-turn  trimmers for adjusting bias voltage to the jfets makes it a helluva lot easier to tame these high gain circuits when it comes to oscillations (JCM800 included). There's a "sweet spot" in both of these circuits that is very hard to get to by using standard trimmers. Yet another tip, once the fet biasing is done, use nail polish to hold the trimmer in it's position. That way standard handling won't change the biasing. These super high gain circuits are pretty touchy.

I saw on another board that you used MPF102s in your build... That would have been my only other possible suggestion to tone the noise down. I have to say though, even commercial boogeys are quite noisy when the gain is cranked. Maybe not this much, but noisy nonetheless.

Either way, I love this circuit and it's the only thing that kept my Krate MX-15R from meeting an untimely death by being "accidently" dropped from my roof. I can't stand the way the gain channel sounds in it. Clean channel isn't too bad, but I don't play clean very often.