EGR valve

I removed the EGR valve yesterday, it was stuck open, return spring works, diaphragm is not capable of holding any vacuum and the expected nasty oil soaked carbon buildup is there. Intake manifold port is remarkably clean, exhaust manifold port is dry black soot, much like the tailpipe. I made a plate and gasket to block off the manifold ports. My question is, do I need to get the EGR valve operational for my engine to breath correctly, also is there any danger of building any pressure that would damage oil seals if I continue to run with the manifold ports blocked off? The only vacuum that is operational is PCV valve and vacuum advance. Both from separate sources. CJ MEDEVAC, if you happen to get wind of this, feel free to wax poetic about your assessment of my issue here.
Thanks to any replies in advance.