Congrats on joining the hobby Bill.
The LT-40 really is a wonderful first time trainer. My son and I both learned on one. It's very stable and will fly well on a variety of engines. The LA engine would not be my first choice because of the lower power. The LT-40 is a big 40 size plane -- almost 60 size actually. If you can trade your engine in for the FX, I'd recommend it. If not, don't worry about it. It will fly on the LA, just without much spirit. Here in Colorado, we're flying at almost 7000 feet and the density altitude becomes a real problem - especially on hot days. The LA engine would probably become a liability under those conditions. I'm not sure what the altitude is in Toronto but I'm thinking you're not much higher than a few hundred feet. Have fun!!