If you have both the Block 25/32 and the Block 50, you can combine the parts between the two kits to make a Block 30 and a Block 52.
To make a Block 30, use these instead...
In step 2, use H2 from the Block 50 in place of Q3 in the 25/32.
In step 6, use A18, H1, H3 and H12 from the Block 50 in place of Q4, Q2, Q1, and Q12 from the Block 25/32.
In step 13, use H4, H5, H9, and H10 from the Block 50 in place of Q6, Q7, Q7, and Q10 from the Block 25/32.
In step 14, use H6, H7, H8, and H11 from the Block 50 in place of Q8, Q9, Q13, and Q14 from the Block 25/32.
In step 16, use F23 from the Block 50 in place of F22 in the Block 25/32.
Other than these parts swaps, use the rest of the instructions from the Block 25/32 kit to make a Block 30. If you have any questions, just ask!