Kewl Go Kart barn find what's it worth

I don't think the briggs came on it but the install was professional,started life as a 5 horse but after they add all the roller bearings and stuff they do I have no clue but learning as I go,I had some homemade ones in the past too and also had a kewl twin engine one when I was younger that mom bought me but the most I ever had on it was a single 3 1/2 horse on it but it was fast and handled like it was on a rail and I was a small kid so I could catch the faster carts on the long haul

Gotcha. It looks great. Somebody did a nice job. I had a home made one with a 8 horse B&G. I lived out in the country and had very little money so I never could come up with pulleys (yeah it was belt driven cause of my parts were free) that would give me a good top speed but man would it do a crazy burn out and stand on the back end. Bout killed myself the first time it went over and threw me in the street when I wasn't expecting it. I made a wheelie bar for it using a push mower tire on it. I could do a wheelie for 100 ft or better after that. Unfortunately it didn't last long though. I was a kid and didn't think about how when it was up on the wheelie the oil wasn't getting on the crank. LOL