Yep, I'd give it a shot and see if it's doing what you want or not. If the OCD doesn't do what you are looking for, you could always try a Bad Monkey or something (these can be had used for between $30 and $40 and have more EQ control than most tubescreamers)
I've used both a boost and an OD on the lead channel as well just to give it some more gain or sustain (depending on what I'm going for). You may get some feedback if you are using a lot of gain on the lead channel and switch on an OD with the gain up high. A lot of how well it will work depends on your setup.
I gve up after many boxs and settings to try and make the Mesa sound like a Marshall and scored a same era (77-78) Marshall JMP MKII 50 watt and just use a A/B box to switch amps.
The Mesa will still blow the Marshall away on volume but not the crunch chunka chunka thump factors.
Now I just need and A/B/C box to add the Egnater Rebel w/Recto Cab or Thiele 90 watt Celestion.
Surprising that tube screamer type pedals are being recommended to get a Marshall sound. Try the MI Crunch Box. It's cheap and completely nails the Marshall sound. I've used that pedal through the clean channel of a bunch of different amps (Single Rec, Blues Deville, DRRI, Stiletto Ace). Nails the Marshall sound every time. Try it out.