Looking at the Sectional Appendix, it looks as if the current track layout is non-idea given that there are several terminating trains and it is used as a place for trains to terminate short.
All roads bidirectional through the station would seem appropriate.
This could be facilitated using the existing single ladder crossing at Speke Junction and by replacing the Allerton West double Xovers with a single ladder. Further connections would also be needed.
My memory may be playing tricks on me, but I thought Allerton West had been remodelled as a single Lead Junction 35-40y ago. Is this true? Has it changed again?