I taught myself to fly using park flyers and then made the transition to glow power.

Before suggesting steps that will increase your likelihood of success with the P-40 I’ll answer the original question.

For that model I would suggest a 90 – 100 size four stroke engine. War birds with 2 strokes seem to lack authenticity. Four strokes can be a little more challenging for a new glow owner, so finding help at the local AMA field is suggested.

For servos, you could get by with standard size basics but you might want to consider a low end digital like the JR DS821.

As I said earlier I learned on park flyers. My progression went

Firebird Freedom
Sig Kadet EP42
Mini Ultra Stick
Precision Aerobatics Katana
Laser Arts P51 Mustang

I flew these extensively until I was comfortable with all aerobatics and beginning to master 3d flight. Next I bought a Graupner 60 size Patty Wagstaff Extra.

During this time I also developed basic building experience with the ARF’s and one full build. That said, I didn’t know much about glow. To help me over this hump I decided to buy a glow trainer, but I really didn’t want to spend a lot of money. So, I watched my local internet want ads (CL) and found a complete Avistar setup very cheap. I flew it without incident and my maiden of the Extra went fine too.

Now a question – what kind of park flyer experience do you have and how do you intend to proceed with getting the P40 airborne?

I ask because the subject indicates this is your first ARF build. You should do fine building it if you take your time and follow the instructions carefully; however it is easy to overlook something on a first build. So, I would recommend you get someone with more building experience to inspect the model before the maiden.

My experience is that the more advanced park flyers are either ARF’s or full builds. You subject suggests you may have flown mostly RTF models, but of course I don't know. The P-40 is a moderately advanced glow plane and a world away from most RTF park fliers. You need to judge your own skill objectively, but I would suggest you consider looking for an inexpensive used glow trainer OR a “second glow plane” like the sig four star. I believe you would find this money well spent as you make this transition.

In summary, 4 stroke, decent servos, find local help, and strongly consider adding a rung to your ladder between your park flyers and the P-40. This rung could be a glow trainer or a "2nd glow" plane if you've advanced enough in the park.