Sometimes engines DO care what brand they are... a strictly chevy guy may not be familiar with chryslers core shift problems (probably why I have a 318 block in here with a 4.070 bore), or a ford guy messing with a chevy or dodge with siamese ex ports and the way the heat can build up there, or oiling differences are vast between different engines and can be very critical, or a dodge guy wondering why the heck chevy BBs have good ports and bad ports (one dumps in the middle of the cylinder and one dumps into the cylinder wall) and the best way to cam around it... thats just a few examples I can think of and I am just a little peon engine builder, there are tons of different engines that do have little quirks that a specialist engine builder may know where a "build everything" guy could not possibly know them all, he may build an adequate engine but a specialist should be able to wring a tad more and probably cheaper. Think you should take your SB mopar to John Kass? Or 351 windsor to Ray Barton? Those guys have incredible mad skills but probably better people out there for those engines.