usually that would be a cast iron master cylinder/reservoir and it would be relatively easy to see which is front and which is rear by the size of the reservoir attached to each circuit. the front brakes being discs would use the larger reservoir. I think I have seen the masters plumbed both ways before, with the stock cast iron master. just ensure the prop valve is plumbed correctly as well.
do you have a stock combo valve in the system? if so, it may need to be reset after bleeding the brakes because the piston in the cylinder of the valve shuttles to one end and closes off the output for the other end. maybe this would help?
https://www.chevytalk.org/fusionbb/a...cf4f54b6ed9df/
http://www.classicperform.com/TechBo...roubleshoot.ht