Selling primary residence- owner financing??

[Jim Stanley]

I am considering selling my primary residence near Denver so that I can use the equity to buy a cheaper residence in another state as well as some STR's.

BUT I have a REALLY good mortgage rate (2.5%, 30 fixed) and I hate to give that up.  Can/should I do seller financing?  How would that work and how do I make sure I get paid?  I currently owe about $320k and the house is worth about $750k.  My payment is $1800/month.

If I sold it for $750k, could I get, say 25% down ($188k) from the buyer plus a thirty year payment at, say, 4% ($2683/month)?  That would give me $883/month  cashflow on the payments, plus $188k in my pocket.  About $40k would go to a 10% downpayment on a 400k house for me leaving $148k to invest.  Please correct me if this is wrong or totally unfeasible.

Thanks!