I have never had a 289, but I would guess with the stock valvetrain, u better stick to no higher than 5500 rpms...but I am sure someone else in here will know this better than me.
I would leave ur gears alone until you get a 5 speed, and focus on suspension and engine goodies. AS for the T.C., u can always call a good company like precision industries, they will ask you a lot of questions on ur car and tell u what u would need.
AS for heads, for budget heads these might be ok
http://thumperoforangepark.com/ or maybe a set of gt 40 heads off of ebay. But after I bought a set of ford heads....see signature, I wish I would saved a little longer and got some good aluminum heads like trick flow.....just my opinion though. Just remember that bigger valves does not mean more power....the rest of the combo effects the heads performance limitations.
Ryan