55.2-59 Gauges help. Engine and transmission finally set

[Missyblue]

We finally got our 91 350 v8 and 4l80e transmission set in the truck after much fussing and trials with mounts and scrapping the frame brake booster. Finally found engine mounts that worked with minor modifications to keep my original exhaust. And ended up making a mount for the trans mission out of part of the donor vehicle. May part of the donor van forever live on under a much cooler ride haha. So now I am struggling to find info to understand gauges. I had hoped to use my original gauges but my mechanic Helper wants me to upgrade to something more modern. I am doing the wiring with my dad but dont understand the options. I have found a electric to cable box form dakota digital that would help with the speedo but it's like $300. Am I crazy and better off just doing new gauges? Not that they are cheap either but I don't even know that mine work.......advice on brands of gauges or thoughts would be appreciated. Thank you