Hello!
Same question I had recently. Many people just add a seven hole adjuster to the forestay at the top by the mast tang, and achieve the desired rake that way. Another guy in our fleet had a custom forestay made with an adjustable turnbuckle down by the bridle connection. His finished forestay length is 23'2.5" . That is with the turnbuckle set to the middle of its range.
Hope this helps!
Cheers,
Tim J.