I'd like to see you try and bring Ma'afu back, he looks to be doing quite well in the north and it be interesting to see how he goes. If he has improved his experience would be invaluable come world cup time. That said he looks pretty settled and might not be interested, particularly if he has to break a contract to do it. There's also Phil Kite who was Brisbane city's third tighthead and went to the vikings to try and crack super rugby. Given Talakai and Faagase's good showing so far he's probably up to it in the set piece.
Otherwise it might need to be an established foreigner to make a quick difference, which would depend on where your allowance sits atm.