There is no such a thing as Sylvania gold grid tubes. What you are referring to are Sylvania tubes with gold plated pins. Some people are getting insane prices for these JAN (Joint Army and Navy) 5654 tubes.
As mentioned previously on this site, inexpensive Sylvania JAN 5654 tubes made in the 60' and 70's are identical to the ones with the gold plated pins, but without the gold plating on the pins, and they sound exactly the same. The way to identify these inexpensive tubes is to look for Contract Number DSA 900 on the box. Here is an example of the print line on the box: CONT. NO. DSA 900-67-C-9983 (This tube is from 1967).
Good luck tube rolling! I myself the have the 6N6P gold grid power tubes together with the Tung Sol 6AJ5 driver tubes, and in my system I am perfectly content to stay with this combination. I did notice that there is a slight variation in the sound between different years of the Tung Sol 6AJ5 tubes. The 1945 ones I tried first were very good, but a later 1960's pair had even stronger bass. The mid range is excellent, and the treble is absolutely gorgeous with crystal clear shimmering highs.
Would like to try the 6N6P-IR tubes, but I am waiting to find a bargain - I never paid more than $8 for a tube yet.