Let’s address the elephant in the CRT monitor: You cannot legally download pre-activated Windows 98 ISOs from random archive sites without owning a license.
Create a new qcow2 image (e.g., 10–20 GB recommended): windows 98 qcow2
The email from the client was short and panicked: "We have a legal hold on the design files for the 1998 Metro interface. The only machine that can read the proprietary format crashed. If we don't open these .prs files by tomorrow, we lose the case." Let’s address the elephant in the CRT monitor:
qemu-img convert win98se.qcow2 -O raw win98se.img windows 98 qcow2
qemu-system-x86_64 -m 2048 -enable-kvm -vga cirrus -device rtl8139 -cdrom /path/to/windows98.iso -hda windows98.qcow2 -boot order=a