The C 150M was the last of Cessna's design changes to widen the cabin. The original 150 was 6" less wide, with a 3" widening in the '60's. Yes, you'll get to know your passenger. But, if the passenger is so large that you can't avoid them, perhaps they are larger than the 150 design was intended for. Though not the most racy taildragger, there's a lot to like about a 150M as a taildragger. In particular, it's one of the most common planes made, so repairing it, and finding parts is easy. The 150 seems to be below the threshold of some rather burdensome inspections which are being mandated. Maybe it's time is coming, but not as fast, nor as expensively as other larger Cessnas. The taildragger conversion is pricey, but if that's what you want, why not!
Larger wheels are okay, though they really do bit into the paved runway, and increase the risk of groundloop. The one I used to fly succumbed to that.