I agree that I'm not crazy about the nylon wrapped gut strings like Golden Spiral. They tend to have low volume, they're floppy and very thick. No chance of bowing them either. A plain gut is a better choice for the G&D. Louder, more durable, more focused pitch.
IMO, mixing gut with Spirocore E&A is a real mismatch. Spirocore is one of the most bright, sustaining, "mwah" strings, sort of the opposite of gut.
Helicore Orch. would be a better match. Some others I've used for E&A that worked well are:
Pirastro Pizzicato - these are semi-flatwound silver wrapped gut. Much better than roundwound gut, more sustain, better pitch definition, and much more durable than other flatwound gut strings like Olive and Eudoxa. Not good for arco though. Also, pretty expensive.
Thomastic Superflexible - A darker steel string than Spirocore. Very affordable. Still a little bright against gut for me.
My current favorite for E&A are the Innovation 140H. These are a flatwound metal, synthetic core string. They have punch, sustain (not too much), comfortable tension, they bow well and aren't too expensive. I'm currently using them with the 140B (braided core) on the top. These are a little darker and less sustaining then the H's for the top. I'm really happy with this combo and can play a wide variety of music, including Bluegrass. But the 140H E&A would mix very well with gut tops, IMO.