Kinda apples and oranges wrt characteristics and depends on what you want. The Axtell kit is over square, while the Millenium uses the 103 stroker crank and their 98" cylinders.01fxstb said:
An oversquare motor is typically going to be smoother and can be built to deliver torque or higher-rev power. A stroker will shake a bit more and is typically a low-mid torker. Either is a strong step up from a 95 in terms of performance and both are more expensive, with the stroker obviously being more so than the 107.
GRock has built a number of 107s and probably strokers too -- and a lot of members here have both. You'll be getting first-hand input soon! Either way ya go, you'll be grinning.