First order of business is to welcome you to the Chevy Chat Site. I think you will find the members to be very helpful and encourage your work with the 490.
Don't hesitate to post any question on the forum. Someone will provide an answer for you.
Firing order is: 1-2-4-3
Timing Gear Assembly: Match marks on cam gear and crank gear.
Running: Find U/C on flywheel and then go to the next mark which may be 25 degrees. Time to this second mark.
It is not realistic to limit parts sources to one area. You need WW coverage. Start with Gary Wallace. (314) 293-1991
Other sources and much data on your car go to TECH TALK and check out HOT LINKS.
(You have posted under the early V-8. Your car is a 490 and should be posted under 12-28 above).