Those are two fine engines. They'll crank right up for you every time. The Black Lynx is the hottest one of that type Matt at Ex Models makes. And Bernie's Cox Int'l Killer Bee II is right up there too. Get some extra head shims, because the head, especially the one on the Lynx, has extremely high compression and you'll need to experiment to find out how many to use depending on your fuel, elevation, and temperature. Using Sig Champion 25%, I've used as many as five shims in the heat of the summer, and down to three in the dead cold of winter(I'm at 300' above sea level). Or with the Killer bee (Cox high comp. head), two or three is usually the answer. If you try different nitromethane percentages, a general rule of thumb is to add a shim for every extra 10% nitro. I feel you will get the best service with about 25% nitro. 35% isn't worth the added stress on it for the small gain in power.
These SPI engines really wake up at the higher RPMs that you'll get with a prop smaller than 6". I like to buy the Master Airscrew GF series 6x3 props and cut them to 5.5" or less. 5" is as small as you'll want to run on it, and will give you the highest RPMs. A lot of people like the Cox black props, commonly called rubber duckies, because they are very flexible and durable in crashes. I find them to be harder to balance than the MA props though. Balance is important at high revs and will prolong the bearing life.
One last thing to add is, with the large venturi on the Lynx and Killer Bee, your tank position is critical and really affects ease of cranking. The shortest fuel line possible is best, and keep the tank about level with the venturi height. Too low won't draw fuel as well and too high will flood the engine easily. I feel the mylar reeds are the best replacement part. Reeds will become mis-shapen after a while. And after initial break-in and a couple of quarts of fuel, keep an eye on the piston rod play. The ball socket can loosen and may need to be reset. After the first time, it won't happen so often.
Good luck, and let us know how it runs.
Rusty