I half-built a Vari-Eze so, not a lot of help vis-a-vis the Long. Basically you will add ballast right at the tip in front of your toes. Which upsets somthing called the 'polar moment of inertia'(think of a sling weapon with a heavy rock at the end of the lanyard). Many Eze aircraft already have ballast up there, and when you increase the weight at the engine station, you'll be adding ~20Lbs in the nose or more.
It will likely increase the PIO tendency, and also the pitch flutter in rain. Not something that the Eze aircraft are good at to begin with. If it has the Roncz canard option, adding a big engine in back is going to be interesting. It's a very low drag airfoil, with touchy low speed handling, and although it won't technically stall, you can develop a really exciting sink rate at high pitch angle that is hard to recover. Think, like the back side of the power curve where adding pitch only makes it worse.
the Long-Eze is a travelling plane. If I were going to change engines, I would avoid the big Lyc/Conti and go straight to the turbo Rotax 914 for altitude performance. But - that's just me, and I'm weird.
