I have built mine with 125hp for about 6k on the engine normally aspirated, in order to do that I'm running a miglia crank, swiftune rods, everything lightened. It's topping out at about 8400 hence my rocker issues. Got the med low distortion rockers now which are fantastic. Reliability is an issue tho, it's running 11.5:1 compression so head gaskets are an issue even with 11 studs. Also using a 7" manifold and a dcoe45 means it will ice up from about 3 degrees downwards.
The turbo engine above could do with an sw5 cam to liven it up a little maybe if he wanted to push it.
As for teg lumps in a mini like I say if your not used to driving a mini you prob won't notice that much but when you are you can feel the difference. The balance becomes even more front heavy, they understeer more but for me feel worse on the brakes as the back tends to wander.
A lightened a series on the other hand does the exact opposite