The '69 351W heads you have are good heads. I believe they are adjustable rockers and not torque down -(look adjustable but aren't --5/16" fine thread studs) rockers. You also notice that you 'll have extra intake bolt holes if you try to run the 302 intake. Some guys leave 'em, some plug the holes, and some grind out the bosses in the water passages slightly increasing waterflow. It's up to you, how you want to deal with it. Seen it work all 3 ways.
As far as a cam- Here's the specs I've been using on several street builds I've done in the past
Lift- .472/.496
[email protected] 214*/224*
Lobe center 112* (110* is ok too)
Intake Cntrline 108* (110* is ok too)
(using a 110 spec will make the cam a tiny bit more lumpy and take away a tiny bit from the bottom end but add to the top end, a 106 on the Intake will definately make for a little lumpier sounding cam)
Use a cam ground with either a 302 or 351W firing order. I like the sound of the 351W (302HO) Firing order and is also said to pick up a few ponies too.
Staying under .500 lift should keep you safe and not have to worry about smacking pistons on most builds with flattop or stock pistons. Also very friendly with compresson ratios 9.0 or lower. You start to loose streetability when you move your duration up higher than 228* thus requiring a looser converter and better rear gearing not to mention a better exh system (headers) to actually benefit from the duration above 228*. Dual pattern cams (like the specs I suggested) seem to work really well on the street and especailly in the small Fords. Single pattern cams work fine, but have a narrow powerband and just don't pull as hard off the line and through the powerband like a dual pattern does... that is unless you have alot of worked-over speed parts bolted on, gears, stall conv., and so on.
Keep the cam and lifters of same manufacture if at all possible.
That '74 block is kind of a turd because it's the 1st casting of the 'tall deck' blocks. in '78 they went back to the shorter deck. The taller deck will add .020 to .030 (depending on the piston that was used) extra depth to the piston down-in-bore measurement, over a short deck 289/302. This drops your compression ratio a point or so over using the short deck block.
The absolute WORST factory 302 was the '77. It was fitted with the "turd-of-all-time" 69cc cyl heads thus cranking out just barely over an 8:1 C/R...
The return of the shorter deck in '78 combined with these boat-anchor 69cc heads didn't make it as bad, but still isn't worth shouting about.
You'll be right around 8.7:1 with the 351W heads and the '74 block.
Pushrods..... my experience... the last thing to buy. Due to different base circle measurements, swapping heads, aftermarket rocker arms, etc.. pushrods are usually bought last because you'll have to assemble the engine and correctly measure for the correct length that you'll need. Yeah sure you can thrown in any old set that is close and it will run, but it could cause you further problems or damages later on down the road... trust me, I know. Again, the cam specs I suggested, seem to work fine with a stock set of rods as long as the base circle of the aftermarket cam is the same as a stocker.
Alot of the engines I have built are "Heinz 57" and as long as you pay attention to what you are doing and making good measurements, you'll be just fine.
Hope I haven't overloaded you with info, just my experiences. Hope this helps out a bit.