I have a 350 bored.60 ,elderbrok carb and intake ,headers,holly return style the,oil and water gauges,hei vac distributor,tci look up kit, what do I need to do it properly and be able to drive daliy and have my rpm,speed,volt,temp on my dash work and use the fuel pump in the tank, and cooling fans to work and if I was to go tbi what would I need and which is better I want it to have gauges in car to work if I can and no check engine light

 

Someone removed your computer system and sounds like they hacked up the wiring harness and you want to know what it will take to put in back right? There is no way to answer that. That is like me saying I have a rubics cud here that is all messed up how do I get it right?

Your 90s gages are not driven by the computer like a modern car. Sounds to me like someone got a little knife happy when removing the computer. Unless you want a hobby for a year or two your best bet would be to sell what you have and find an un-molested car and do the research and upgraded to the level you want in a way you like. OR find a wrecked L98 (350 TPi) and transfer everything from that car to yours.

If you try to fix this one every circuit and mechanical system will be a puzzle. For a trained mechanic It is easy to fix a “normal” wear car, there are only so many things that can go wrong from time and wear. Once you let a hack loose on a car there is no limits on what could be wrong.

 

no miss understanding computer still in car I took out the 305 and installed the 350 you said it sounds like i was done with the parts I had I what just wondering if it would effect my dash gauges but would I need to do something for cooling fans to operate properly

 

Your computer may still be there but it is useless since it not hooked up.

What you are asking is too much to type. Maybe I can get you started and others will add in. Step one will be getting a GM manual with wiring schematics. Also you will be attacking one issue at a time. By taking these smaller bits it will be a easier for you and to help you. You will have to look at everything that does not work one thing at a time. Make a list of everything that does not work and set a priority.

There are three or four ways to handle the fan. I would do it with a thermo switch and a relay. I have seen people just add a contact switch to the carb so the fans run when ever the throttle is at idle.

Oil pressure gage, You will need to find the old pressure sensor connector and the old pressure sensor. Install the old pressure sensor in you new block and hook it up. Same procedure for the coolant temp sensor.

Voltage gage should work. If not you will have to figure out the wiring harness, find the most convenient place to cut the wire and feed that to your Key on hot side of the fuse block.

The engine harness and the computer harness are in some ways intertwined but if you are carful you can remove the computer harness and keep the engine harness.

Speedometer, The way the older computer system worked the trans speed sensor drove the speedometer and the computer fed from the speedometer at some point they switch that up and connected the speed sensor to drive the computer and then the computer drove the speedometer. Step one for that would be to look at the wiring schematic or read the description in the GM manual for the speedometer.

There are still ton more things I can think of and I am sure many I did not thinking of.

 

A Haynes manual from the local auto parts store will help you a lot.
City libraries may also have schematics in the Reference Section and you can reproduce them there and/or take a pictures of the pages.
Better drivability would be in keeping the TBI system and get ECM to work as it would learn the 350 from the 305, providing the new 350 has a stock configured camshaft.