I went to Lordco Lori and bought a lysle spill proof funnel. it has an adapter for the radiator and a 45° adapter to kèep it level, put that on your after removing rad cap. I had to use an additional rubber seal the the top of the adapter as its not a tight for and you don't want coolant leaking on the ground. pets and stuff love it as its very sweet.
add coolant and or water into funnel so say...2 or 3 " are sitting in funnel. start car and let idle, as it warms (engine), your thermostat will open allowing circulation of hot fluid from block to rad. it will bubble like a bugger just keep coolant up and adding as needed. as soon as your up to temp (195-200°) shut er down and don't let it overheat or it will puke everything out. it helps having someone in he cockpit ready to kill the engine as you watch coolant levels and bubbles. remember coolant expands as it heats up. Just just dont let the level get low enough to reach cooling fins in rad. the funnel has a nice plug that will fit he funnel throat so you can pull it off after cool down and return any extra to antifreeze jug if you have one kicking around. check levels for the next few days before you hit the road as as it cycles thru the system it will more than likely lower a bit. keep topping er up in the morn. 2 days I was satisfied it wasn't looking any as i made sure coolant overflow tank is filled as per requirements on bottle. Hope this helps and try the 2x12s for ramps on passenger side,. the heater core is higher than the rad. ,air can hide there easy. you should hear no gurgles when its hot and sealed with a rad cap.