Welcome to the forum calstatechico, you've come to the right place
I'm all about 4-strokes these days and can recommend the Honda gxh 50cc or it's clone the Huasheng 49cc. Another nice little 4-stroke is the Harbor Freight 79cc and it's rather affordable price tag. I've had good luck with these couple of engines and there are more out there that are worthy as well.
As for a front suspension fork, most decent Mt. Bike forks work well, just be sure to get the correct size steerer tube for the frame you are going to use.
Don't be afraid to ask questions, there's plenty who can help you here.
EZ Motorbike Dealer - San Diego, CA.
Nothing is out of my realm,
if it doesn't fit, make it fit! Beer is the answer....what was the question?
A sense of humor
costs nothing, why don't people use them more often?
"You can't buy respect.....you have to earn it"