I just bought a 83 chevy 3/4 ton with a 454. how do i know if it is a tall deck block or not? i bought the truck for the engine to build for a race car. what are the pros and cons of a tall deck?

Unless it's been installed by an idividual, the 3/4 ton (2500) did not get the tall deck ("heavy duty" truck ONLY). You can look where the water pump is installed. If there's about 1/2" of material ABOVE the pump, before the deck and head come together, it's a tall deck. Less than 1/4" between if it's the standard deck.

The main advantage of the tall deck block is that one can add a MUCH longer connecting rod. The longer the rod, the better the "rod angle". The rod/stroke ratio of 454 is pretty woeful with the stock 6.135" rod. By using a 6.7 or 6.8" rod, things get better fast.

Main "disadvantage" of the tall deck? It takes adapters to use an intake manifold from a standard deck. Not a problem, just an "issue". The carb and air cleaner will sit about 1/2" higher, too.

Jim