I have one that isn't along quite as far as your plane. Mine has the foam wing. It looks like you have the wood wing, which wing do you have? You can tell by measuring the span. He did plans for the scale wing, as well as the sport wing. The foam wing is in between in span. what retracts do you have? I have talked to Larry quite a few times about this plane. I am building mine of the Kfir C-2 that gets you the Canards but you need plans to understand what I am talking about.
I have seen one flown with the New K&B .48 which I think Larry is trying to market but K&B is being a-holes about engines. It flew OK not very fast. I am using a BVM fan with a KBV .82 for power this should be good power for this plane. I am using B&D retracts which are an old design.
Your profile says you are a JR member which I take to mean that you are a teenager which meen $ are tight. This may not be the part of the hobby that you try to do on a shoe string, a lot of things go wrong in a jet that need the extra effort and money that doesn't leave much room for error.
I would discuss the engine issue with Larry when you talk to him. It depends on which K&B you have as to how well it will work. If you have the box the engine came in get the model number from it. Some of the K&B's were really bad and took a lot of skill to get to run well.

Sparky