think the rope is a bit small, its better to seperate the rope then wait it grow to a suitable size before joining it with you senegalus, the rope might have trouble competing for food
1.5ft ropefish is a big one. The max I've eye witness is 1ft. Anyway, think it won't have any problem been mixed with bichirs. Btw, it needs hiding spots more than any bichirs do, IMO.
I've had ropes as small as 8" with 8" senegals with no problems. No problems feeding either (the ropes eat out of my hands). They pretty much ignored each other.