351w or 302 engine build

I think you may be better off getting a crate motor for the money. Ford makes a 393 (I think 351W based). You could run a shift kit w/ a Z gate shifter in the C6. I have no experience w/ a C6 but I've heard they absorb too much torque, which makes me want to thing they are sturdy enough not to fool w/ clutches, just a shift kit and bands. The Z gate shifter is cheap but you can bank the crap out of them and the hold up.

BTW I did a build from the block up in 1992 (engine still runs great) and sunk 3-grand into it. It seemed like as soon as i got it in the car and runnin the market flooded w/ aluminum heads and crate motors. If I could do it over I7d go w/ a long block crate from FoMoCo. I've always heard good things about the FoMoCo engines. Oh yeah w/ a crate you get a guarantee, your own build you take it in the shorts if you make a mistake!! I know. I snapped a rod bolt during assembly due to over torquing so I had to get all of them replaced.

parts for both motors are relatively the same cost. rebuilding you current motor will save a little if you can reuse some of your parts like exhaust headers etc. comparable builds the 351 will make more power and will have better street manors. i would go with the 351

I would say it depends on your power goals. For instance, I am currently planning on staying 302 based motor in my '70. I might do a 347 stroker at some point, but I'm ok with limiting my power to under 400 hp (very safe range for longevity in a stock 8.2" deck block). For me with a convertible I don't want to get too crazy with power. If you like to turn corners - handling will be better with the 302.

If you want to race or have higher power goals, go with 351C. 351W is ok too, but it was built more as a truck/passenger car motor whereas the 351C was built by Ford for performance. Also, the Cleveland came as an option in the '70 Mustang, but the Windsor didn't. If you are planning to really push performance on a low budget, the W is cheaper to build with aluminum heads and all the extras. However, you can easily make 400-500 hp on pump gas with a Cleveland using the factory iron heads - that's an inexpensive option for good performance.

Since you already have a 351W, you might want to build another - especially if you have a lot of aftermarket parts on the one you are using.

The C6 is a good transmission. They are tough and inexpensive! The C6 does suck some power, but for pleasure driving it might not really matter to you. If you run a lot of highway miles you might want OD. Then there are several options as well which all depend on power. If you keep it below about 400 hp it's a lot cheaper to build an AOD that will last.

You can buy a c4 from summit for around $1000 that will hanlde up to 450 hp with shift kit already installed. Thats what I did on my 347 that I put in my 70. I went with 302 since I was doing a boss clone but if I wasn't worried about that I would have went with 351. Bigger stang has plenty of room for it and upside from power is better.