If you had time for some ‘test’ batches consider experimenting with number of a 1 gallon batches (brew a five gallon batch and split it into smaller batches). It’s ‘easy’ to bump the ABV with sugar (see this thread) in the one gallon fermenter. The book Brewing Better Beer (chapter 2) offers some alternative approaches to steeping grains that may be helpful when brewing small test batches with different amounts of steeping grains. Finally, pay attention to the hops / gravity ratio so that it is reasonably consistent between the original recipe and the scaled-up recipe. .
