Intentionally slow one main to speed steam to other main?

Motorapido

I recently removed the ancient, slow-venting, designed-for-coal main vents on my single pipe steam system. The longer main takes about 3 minutes longer to get steam than the shorter main. I would like them to get steam at the same time, or at least close. Here are my measurements:
65 feet of one single main runs from the boiler to a point where a branch connects from a riser off the main. Branch is 2 inch. Main is 3 inch. From where branch leaves main to end of of the branch is 60 feet. So I count this main-plus-branch as 125 feet. This 125 foot section feeds 12 radiators (8 from the main and 4 on the branch that connects to the main). After the branch connects off the main, the main continues for 27 feet to its terminus at a return. That 27 foot section of main feeds 2 radiators. On the 125 foot section, I have 3 Barnes and Jones Big Mouths. On the 27 foot remainder of the main, I have one Gorton #1 and one Big Mouth. The 27 foot section gets steam at its vents about 3 minutes faster than the 125 foot section (65 feet of main and 60 feet of branch). Have I over-vented that 27 foot section? Should I remove the Big Mouth and plug the hole, leaving just the Gorton #1? It seems that doing so would get steam to the longer section faster, since the steam would want to travel through the pipe with the least vent resistance. However, this would somewhat fly in the face of the dictum to vent your mains as fast as you can.
My primary reason for wanting to get steam faster to the longer pipe is that the 60 foot branch serves a large bedroom and full bathroom that is built over a crawlspace (original to the 80 year old house), and its 4 radiators. The remainder of the two-story house sits on a full basement. The bedroom/bathroom over the crawl space stays quite a bit cooler than the rest of the house since I keep the door to it shut, the room has more windows than elsewhere in the house, and despite sealing the foundation and foam insulating along the sill band and encapsulating the crawl space floor and walls and sealing up the foundation vents, the crawl space stays a bit cooler than the basement.
Please advise on my thought about slowing the venting on the 27 foot section of main to encourage the steam to move more quickly into the long section and the branch in the crawlspace, and its capacious 3 Big Mouths. I would think the steam would already be rushing faster into that pipe, despite its length, since it should be excited to flow out of those 3 huge Big Mouths.

Motorapido

Oh, I should note that I have about 2 inches of fiberglass insulation on the branch through the crawl space and the pipe pitch is reasonably decent. I adjusted the pitch with clevis hangers and got it almost perfect, but it bumps into a few cast iron waste pipes that create either a wee bit of upward hump or belly sag, but not enough to cause any significant water hammer. It seems to send its condensate into the return pretty well, and again, no big water hammer. At most, a tiny bit now and then on fully cold start-up.

Fred

Are the pipes in that crawl space insulated? Try taking the Gorton 1 off and use just the one bigmouth and see if that helps the timing any. I doubt the Gorton #1 is enough, by itself but you might consider changing out the Bigmouth for a Barnes and Jones Vari-vent. It can be adjusted up to about 2.5CFM and downward from there to help balance the mains.