When I started track in 2009 (after two races in 1992) I was on a 7 lbs frame/fork/headset (99g Omas headset so the frame/fork was 6.75 lbs - we joked it was sewer pipe). I bought the frame fork from a rep for $99 - the rear triangle had been crushed at some point in its very short life so both dropouts were 100mm locknut to locknut. When I saw that I thought maybe track bikes had interchangeable front and rear wheels. Then the one guy in the shop that did track said, "Oh, it's supposed to be 120mm. Here, grab this drop out, I'll grab here, and on three just tug hard." Voila! 120mm drop out!
Anyway, I raced that in 2009. I had the same rear hub I bought with the bike (Superbe Pro, so it was nice, but a 32 spoke old school thing), and I threw on a TriSpoke front wheel that I bought in 1990 or so. It was definitely enough to dip my toes in track racing, and I had fun racing. Wheels make a huge difference when going fast (rider position is a huge factor), so I'd get a TriSpoke front and some rear disk wheel. You can get relatively inexpensive disk wheels used, and front trispokes are cheap too.
I now have a fancy bike, did some racing, and I am no better than I was in 2009. In fact I'm probably worse. But the sleek modern bike sounds cool.
On the "rain on your parade" side of things.. the M50s in SD will be really, really, really, really fast. I'm just saying that based on who lives in the area, not because I have experience racing there. You're probably better off racing the 4s and 3s. I don't know though - that's for you to discover I suppose.
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"...during the Lance years, being fit became the No. 1 thing. Totally the only thing. It’s a big part of what we do, but fitness is not the only thing. There’s skills, there’s tactics … there’s all kinds of stuff..." Tim Johnson