Jerry, pics go a long way.
The typical raceline rail is part of the pressurized cooling system with the upper hose neck attached to the top of it. Sometimes there is a fill cap on the neck.
1) You need an overflow/catch can connected to a small nipple near the radiator cap. The cap releases coolant at this point when the pressure exceeds the cap rating, usually every time the engine is shut off.
2) You need a fill point at the high point. It used to be the radiator in older machines.
An expansion tank is not required but is more effective at eliminating air pockets if mounted to be the highest point in the system. '60s Shelby cobras had expansion tanks. I've used this one for VWs but you need to make a bracket to hold it up, not just the bolt flange. It tees into a heater hose fitting:
https://www.ebay.com/itm/333816653050?_ ... BMmoX7-Kdf
_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS
viewtopic.php?f=5&t=13225&p=134742Simple Spring select
viewtopic.php?f=5&t=11815LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12