I don't know what 'upgrades' a standard kit would need, but I looked at their kits some time ago. They offered me a pretty good deal on bulk prices, and their motors appeared good, but I decided not to bother because of their carbs. I don't know if their new speed II carbs work well, but I didn't like the fuel inlet sticking straight out of the side or the air filter that turns pink in about 3 weeks in the sun. Also, I have lot of engine parts on the shelf that won't fit their longer rod motors.
In this area, I've only once seen a skyhawk motor with the long rods and don't want the hassle of stocking both kinds of parts - same with super rat motors with built-in CDI.
As a repair shop, these things are important to me, but as a customer, I'd guess you will be OK though.