ideas on wire routing

[james69z28]

I am building a 1971 show truck and it was partially started when I bought it. My question is the previous owner smoothed the firewall and other than the power brake booster and emergency brake cable there are no visible holes, they installed vintage air in it and put the bulkhead fittings in the side of the cowl to be hidden under the fender.
I am constantly trying to figure out where to run the wiring and speedometer cable out of the cab and I have a couple of places in mind to drill holes in the floorboard and use rubber grommets to get the underhood wiring into the engine bay and also out to the rear lights ect.. I was just wondering if any of you had experience with this and if you had a good location and/or likes/dislikes on where you did it?