What block are you using? If you are using the Dart or the Bowtie block then it will be tight, because I think they both use the 0.300 longer lifters. They sell roller lifters that are even longer for the short base circle cams $$$$. (I think that it was 450.00 for CompCams vertical bar lifters)
I put an engine together with the Crane horizontal spring loaded lifters and the Dart block and the springs were compressed almost completely. It turned about 7300rpm's for two years without problems. You have to be careful about the lifter compressing completely against the link plate, but not touching the cam lobe, therefore giving you more valve lash than what the feeler gauge shows.