Frankly, those early C8s are outstanding if you've got a good one that shows nice sharp stars and a good diffraction pattern. They make a Hyperstar for the C8 but given how big the G1 is it works best on a C11 or larger since it's up front and in the light path.
OK I'm googling and learning all sorts of new things.
I didn't know what a Hyperstar was.
Oh and also, if the glass and mirror are flawless on your C8 do bear in mind that a new mount can be had pretty inexpensively. Here's a picture of my M8 on a mount that I got for free by using airline miles:
I'm going to look into this. The original fork mount and clock drive of the C8 weren't the best, there is a bit of play, etc. Having a precise clock drive makes all the difference especially with an f/10 optic and long exposures.
I got out the C8 this morning and looked it over closely, it still looks new (I've had it about 30 years now.) The mirror was very clean, I had to clean the front glass inside and out, however. Then I did a preliminary daytime collimation, which I think will be pretty accurate, although it might need some fine tuning (once there are actual stars out, which won't be tonight.)
If you've not looked through a new eyepiece lately you might find that the biggest improvement you could make with your lovely old C8 would be to simply pick up a nice new eyepiece for it. They've really gotten much better in the last 10 years or so.
I am sure you are right. There is nothing much to improve upon when it comes to mirrors, but the eyepieces are another story. I have the following:
Celestron K. 40mm (Kellner I presume)
Celestron K. 25mm
Meade 20mm wide angle
Meade Or 16.8mm
Or. 12.5mm (no brand)
Or. 9mm
Or. 6mm
Oh, and I found my Meade camera adapter and OM T-mount.
I used to use an OM2 with the off-the-film exposure which was great for astrophotography...but I think the G1 might be a tad improved.