Computing a Gram matrix and a large-dimensional matrix inversion accounts for most of the signal detection complexity in massive MIMO systems. When massive MIMO schemes are combined with Single-Carrier with Frequency-Domain Equalization (SC-FDE), employing powerful iterative equalizers like the Iterative Block Decision-Feedback Equalizer (IB-DFE), the matrix inversion operations need to be computed for each iteration, which further increases the receiver complexity. To avoid the exact matrix inversions in IB-DFE receivers, an alternative structure of IB-DFE is proposed in this work. The proposed IB-DFE receiver allows to incorporate the conventional iterative methods such as Richardson iteration, Gauss-Seidel iteration, etc. to replace the exact matrix inversions in the IB-DFE receiver. In addition, this work proposes Chebyshev accelerated Richardson iteration to improve the convergence rate of the conventional Richardson method and incorporates it with proposed IB-DFE receiver. The simulation results show that the proposed approach can significantly reduce computational complexity compared to the state-of-the-art methodologies while still obtaining a bit error rate (BER) performance similar to that of the conventional receiver.