ive never heard of it b4, theoretically an aftermarket company can easily modify or make their own cast of a bseries tranny to mate up to the block but it would be expensive, ive never heard of anyone modifying anything except the old wagon 6 speed but that was pretty pointless due to the extra gear being for super low speed and extra torque. but hey anything is possible. i know of no direct swap so id have to give u the answer of NO... ?
4 grand for a new mugen tranny would be cheap actually id expect it to be much more expensive which is probably why ive never heard of anyone doing any such thing. there probably wouldnt be a big market for something that expensive, better to maximize the 5 gears u do have with a gsr or type r tranny which i believe has closer gear ratios than the b16 but i honestly dont remember, i do know that my zc tranny (my preference) is as close as it gets to overlapping gear ratios. i love reving it to near 8k and then having it drop to 5.2 or so only to fire right back up with no hesitation. i love the control.