MGB: HELP WITH WIRING: 77 MGB STARTER ISSUE

I am having a where the starters clicks away when I try to start the car. I have now checked two different starters, the original and a GR from www.britishstarters.com. I also have used two different batteries that are fully charged, still no joy. what I have done is I just put my whole drivetrain back in after servicing the transmission. I think what I am narrowing my issue down to is more than one wiring issue. First, I am sure there is supposed to be a grounding strap/wire somewhere between the motor/trans and the body or direct to the battery, but I don't have that installed because I don't recall where it is supposed to go.
Also, I have been going through my wiring, and a lot of my connectors are in really bad shape. So I have begun replacing them with new connectors, cleaning the wires with steel brush and sandpaper, and adding solder in some spots such as the starter/battery to alternator connection on the starter.
So if anyone has experience with the starter issue really being about quality issues in the wiring, I think it would be helpful.
And, if I wanted to directly juice the starter solenoid by jumping the battery + to the solenoid, is there a chance that could damage the solenoid? I have never done it before so I am trying to be cautious before I burn up my new starter. Thanks.

Are u sure the starter is clicking and not the starter relay? Take off the new starter and have it bench tested. The ground strap should be connected to the One of the bell housing bolts and the body of the car.

Wager to say, the missing ground strap is the reason. The starter is a huge amperage draw and without the strap there is too much resistence. You can test with a temporary block-to-ground connection - say a heave jumper cable.

Ground on 77, rear trans mount to cross member.

Yep, no joy 'til you get the proper ground connected up. All new connectors can be had as well. Check out tech tips on back page of Moss catalog.
Also good info here:

Thanks for the input. I am going to ensure I get a ground strap installed correctly, and then test again. I will update as soon as I complete that work.

Well, Mark was absolutely right. I installed a 4 gauge ground from the bell to the tranny crossmember and the starter is now kicking over like a new born baby.