Contact Remington Customer Service through their website, and ask for an owner's manual for the 550-1. Its free. Difficult to explain without pictures. If you have taken the trigger and action apart, you would be advised to put ALL of the parts in a bag and take it to a gunsmith. It will not be the first "gun in a sack" he has seen- trust me.
Last year I paid $550 for a very good condition used Rem 650 .270 win.
Remington Model 550-1 does not have serial numbers.
100-425 USD
$550
50-550 usd
Yes
serial number on 550-1 remington 22 rifle
25-180 or so
Good rifle
300 or so
.284
No, they are not interchangeable.