Bleeding help - dry system

[Chad-1stGen]

Hi all,

Trying to bleed the brakes on my 68 Camaro from scratch and so far it hasn't gone that smoothly.

Running a cast iron master cylinder 29969 casting which I belive is the early vet style booster, not sure of borse size.

aftermarket 5 port proportioning valve.

stock front disk
touring classis rear disk (C4 model)
Stock styled lines - 3/16 fronts, 1/4 front to rear, and 3/16 rears.

I bench bled the master cylinder using fittings with holes back into the resevoir. Took about 45 minutes but finally got all the air out.

Bleeding was done old fashioned way with two people and a clear line into a bottle of fluid.

Ok so I started bleeding the car (furthest wheel to closest wheel). Overall I haven't had to many problems with round 1 of bleeding. I did discover a few loose fittings that I had to tighten which caused the 1st wheel (passenger rear) to take a long time to bleed. I got fluid to the caliper pretty quick but took a ton of bleeding to get no air. Other 3 wheels went pretty quick.

After the last wheel I tried the pedal and it sinks right to the floor and provides very little brake pressure. I can spin a tire with the brakes applied no problem and if I spin a tire and then apply the brakes I hear the pads rub the rotor slightly but they don't even stop a free spinning tire.

Sooooooo. Should I continue bleeding this thing or check something else?

Thanks