the brass, organ and guitar part of the original after school special are very hard to replicate with modern vsts. omnisphere has some good guitar samples and an arpeggiator but it never sounds as full and organic like the original. the closest samples i found to the brass and organ are in yamaha's keyboard vsts. if you layer a few of them it sounds pretty close.
given the limited tools at your disposal, you managed to nail it almost perfectly. hard work surfing vsts really pays off