Yes, your solution is to flip the setup around. Here is what a Cannondale setup looks like, Mine are all black and your are black boss with chrome.
Cannondale downtube boss assemblies are gold.
You will need a flat shifter boss cover not a curved one to make it work.
FWIW, I can't imagine index shifters that could be worse than those Sunrace shifters. I put a set on my wife's bike years ago... for one ride. Total garbage.
John
Edit added: Microshift makes 8 speed downtube and bar end shifters. I have not used them, but I have heard good things about Microshift shifters. I just checked on eBay.