Can't quite agree with Bluey on this one.

The 4T60 isn't really weaker than the 4T65. It's a huge heat generator though. (no, I'm not a 60 fan)

If you top swap, tuning is the key to it holding up. Lots and lots of tuning. An L67 swap will be more lenient tune wise. The added power from the top swap is nice, but the tuning responsibility needs to be taken into account.