which motor to use

Sorry it's been awhile. My Daughter got married 2 weeks ago and we had to go out of town for a reception. I since have received car and motor here's what I know.
Date code D098,block cast 9790079, motor displacement 350, heads date E038 and head has a 17 which is 2.11/1.77 I believe.
So basically a base 350. I would like equal power  to my firebird 400 (stock)
but also good reliability. I want to just hop in and go cruising. No constant tinkering "It's a convertible" and also has 2 speed powerglide.
I hope that's enough info. I would appreciate any advice you can give thanks Darin  

You have a 9.2:1cr 265hp 350 and the #17 heads have 1.96/1.66 valves.
It would be best if you found a better set of heads like the 12,13,48,62 or 670's all heads listed have 72CC chambers and 2.11/1.77 valves team that up with a lunati cam and lifter kit P#Lun-00072LK it has a .458 lift and produces good low end torque a set of headers and a edelbrock performer intake manifold and a 750cfm carb. and a set of 1.65 ratio roller rockers will make a stout combo.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Lose the 2 speed first and foremost, it will drag your whole performance goal down. Also it is a Super Turbine 300 (Buick design), not a Powerglide which was Chevy's design. Swap it for a th350 or th400 or a 200-4r if you prefer overdrive. The th350 and 200-4r are almost a direct bolt-in for the st300, being the same overall length and spline size. The gear ratios in either the 3 speeds or 4 speeds are much more performance oriented than the st300 which only works well with really steep rear gears for the strip.
Steve  
Trying to help... 'cause we don't all have to learn the hard way!

Thanks I wil  go with that advice and start looking for new heads and trans and will probably have more ?'s later thanks Again for the info.  

No problem anything else just ask.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races