I like R's moves.
I would tweak them a bit though to create a bit more delay, increase the stack size in Brazil for next turn and add an attack on Bolivia (adding to the odds that we have one target in SA next turn when we use the OP and a bigger stack to hit that target with).
SUGGESTED TURN 1 (conservative Brazil stacking for OP attack next turn - stronger attacks into CA this turn):
Deploy 5 to Nunavut, 1 to Nuuk, 5 to Columbia, 11 to Brazil. Attack/transfer to Colombia with 6 armies from Venezuela. Attack/transfer Brazil with 16 armies from Venezuela. Attack Northwest Territories with 7 from Nunavut. Attack Quebec with 4 from Nuuk. Transfer only 1 from Brazil to Columbia. Attack Nigeria with 4 from Brazil. Attack Panama with 5 from Columbia. Attack Cuba with 5 from Venezuela. Attack Argentina with 3 from Brazil. Attack Bolivia with 4 from Brazil.
I expect Imp to defend Argentina and maybe try a late move into Bolivia to give himself two spots in SA. My goal this turn is to end up with one target next turn to hit with a big stack from Brazil. The Brazil stack would be 17 next turn with these orders, so we could use the OP to hit with up to 33.
Assuming we want to be sure we get Canada next turn, we'll need between 9 and 11 (depending on how we do on remainder rolls). With only 17 income that leaves 6-8 available to add to the OP attack in SA. If Imp is serious about holding SA, and we'd be foolish to think he isn't, 22-24 probably won't be enough to take out his stack.
I could cut down the attacks into CA to 4s, skip the attacks on Argentina and Bolivia and change the delay transfer to go from Columbia to Brazil. That would add 11 more to our stack in Brazil next turn. Assuming Imp puts 9+ in Argentina, 33-35 might be enough to take him out in one shot. We'd also have another 6 in Columbia that could be thrown in as a 1-2 punch. Alternatively, depending on the what happens next turn, it might make sense to forego Canada for a turn if we think we have a sure thing with the OP to get SA. We could also skip the Nigeria move for another turn although that seems like a popular idea.
SUGGESTED TURN 2 (extreme Brazil stacking for OP attack next turn - weaker attacks into CA this turn):
Deploy 5 to Nunavut, 1 to Nuuk, 5 to Columbia, 11 to Brazil. Attack/transfer to Colombia with 6 armies from Venezuela. Attack/transfer to Brazil with 17 armies from Venezuela. Attack Northwest Territories with 7 from Nunavut. Attack Quebec with 4 from Nuuk. Transfer only 1 from Columbia to Brazil. Attack Nigeria with 4 from Brazil. Attack Panama with 4 from Columbia. Attack Cuba with 4 from Venezuela.
This would get us to 25 in Brazil next turn. It leaves 7 usuable armies in Brazil rather than attacking Boliva and Argentina with them on the premise that Imp will stack to defend Argentina. Even if he puts 100% of his income in Argentina this turn we'll have a sizeable size advantage and an OP card which would make a 1st move stack attack very rewarding.