Ahhh, Brian, always a subtle as a sledge hammer on fine crystal...
Trev, all is not lost on your 127. The trick with any scope is it will have some things it is good at, others not so much. While a spherical mirror ain't great, what it does mean is the scope will do best at low to medium magnification.
I have two of these spherical mirrored scopes myself. One of these (a 76mm Celestron Firstscope) I use as a big finder on my 17.5" dob. I even made a set of crosshairs in an old 25mm EP I had for it. It is bloody marvellous as both a finder, and it does really well on its own as a little scope. You see it on the 'back' of the big beast in the first pic.
The second spherical mirrored 'horror' is the kids 114 f/4.4 scope. I made a table top dobbie mount for it where it is fantastic out bush, and I also use it as my video scope at public star parties. Damn brilliant video scope it is too! I rigged it up onto an old Meade fork mount that was about to be scrapped, and made an equatorial wedge for it, and it is an outstanding video rig. It can show galaxies on the monitor that are now invisible even in large scopes due to light pollution in the city. And it reveals colour in nebulae. The second pic is of another scope like the kids' that I made a table top mount for - looks just the kids' mount. The third pic is of the scope being used for video astronomy, and the fourth pic is a snapshot image of M42 I took with it last week.
I've learnt not to 'hate' these cheapies. Instead, I've found their sneaky strength, and I work with it.
Trev, don't feel disheartened with the scope of yours. Just understand its strengths an you will be rewarded. High magnification isn't all what astronomy is about. There is much to be said for low power, rich field work. My latest scope acquisition was also my smallest aperture, a 100mm achromatic refractor. These are not great for high magnification, but that's not what I got it for. I got it because it gives me WIDE expansive views at low power. In fact, next dark sky site trip I'm making, the 17.5" will be staying at home. I'll just be taking the 100mm refractor an just the one low power eyepiece. That's it. Oh, yeah, and my sketch pad...
The 15mm and 20mm Superviews are fine eyepieces that won't kill the piggybank. But like I said, I'm not sure if they will be the best match for your scope, but they will be rip snorters in what ever scope you get next. The one eyepiece that WILL excel in your 127 scope is a 25mm plossl. Plossls were the bees knees of eyepieces 30 years ago, but newer designs and glass technology has seen them be relegated to 'beginner' eyepieces. The one major problem with plossls is as their focal length shortens, the eye lens (the lens you actually look into of the EP, the lens at the other end is called the 'field lens' as it faces the field of view) becomes smaller and smaller, and you need to get your eye closer and closer to the eye lens until with the shortest focal lengths you need to park your cornea on the blasted eye lens to see into it. BUT, the thing with plossls is they are good optical match with Newtonians, and the 25mm is a great match for scopes with a spherical mirror.
Yeah, a bit long this post, but there is a lot to say and explain. This stuff is not mystical - it's just taken me 30 years to figure out a thing or two. And if I can put it down, it will save you time and money as you'll make more informed choices,
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Mental.
PS, the eyepiece set you put the link to, FORGET THEM!!! Those are a waste of money - they are all compiled of old technology eyepieces that cost jack to produce, and are sold at a criminal mark up to the unwary. Sure, SOME of the individual elements will be fine from some of the kits, the asking price for these kits is insane, and most elements are poor compared to even the cheap new eyepiece designs currently available.