Complex sentence: Converting a two-valve TR7 to the four-valve Sprint specification is relatively simple, compared to conversion to TR8 specification, because the TR7 and TR7 Sprint share a virtually identical engine block.
Split into simpler sentences: Converting a two-valve TR7 to the four-valve Sprint specification is relatively simple, compared to conversion to TR8 specification. This is due to the TR7 and TR7 Sprint sharing a virtually identical engine block.