Here's the deal. I have a 400m in my '67 f100, but it has a '73 400m with a small bellhousing bolt pattern for the FMX, not the C6. I have found very few 400's local, but can find more 351w/351c available.

I can get a running 302 and 289 short block for parts for $100. To get a 351w/c or 400, running or not, it'll cost me $350-800, depending on mods or other work done.

Now to the questions. Is it worth spending the extra $$$ for the 351-400? If intended for future minor mod street rod/show truck, what is the better option? more budget friendly? easier to built and find parts for?

 

The 302 and 351W will be much cheaper to rebuild than the 351C or 400. However the 351C/400 is generally considered a more attractive engine due to it's pent roof valve covers.

Your small bellhousing 400 is more desirable than the regular big bellhousing variety. C6s with this small block pattern are readily available (from vans or trucks). So it is a reasonable option to rebuild your existing engine. I assume that you want to replace your FMX with a C6.

 

I have seen quite a few of my friends' FMX trannies go to crap on them under only mildly built engines. I totally forgot about the small bellhousing C6. All I've been seeing is large bellhousing c6's around so it slipped my mind. The only thing I hate about my 400 is that it's a '73, so they killed the timing and compression starting then. I am looking at a set of Aussie heads when they get them back in.