Getting back to PlaneBoy 576's question: Yes, an OS 46 LA would fly the model adequately (just). You may, however, find its performance disappointing -- both with the trainer, & in follow-up applications

Other excellent inexpensive choices are:

TT 40 Pro
Magnum XL 40
SuperTigre GS 40
TT 46 Pro

The three 40-size engines are similar to each other in output (impressive), with the TT 40 Pro having a performance advantage using most real-world propeller sizes (the sizes suitable for your trainer), while the Magnum & ST have a very small advantage over the TT if using small-diameter racing props -- which may be of interest to you later on.

The TT 46 Pro, all things considered, is one of the best 46's in production today. It offers outstanding power, reliability, durability & ease of starting & tuning at a very competitive price.

Also to be considered is the OS 46 AX, which matches the TT 46 Pro in power & quality, but at a price premium that you may, or may not be willing to accept.