After trying to get the imagewriter to fire the pins in a "simple" way which didn't work properly, why not try to hook up a 74123 according to the schematic.

It wouldn't fire at all until I got the right values for the R and C which didn't appear on the sams schematic correctly, but were specified on the apple schematic as .022uF, 18K ohms, and 1000PF, 10K ohms:

Code
	TTL74123(config, m_pulse1, 10000, 1000e-12);     // second stage (hooked up to 1 section of 74123)
	m_pulse1->set_connection_type(TTL74123_NOT_GROUNDED_NO_DIODE);
	m_pulse1->set_clear_pin_value(1);  // not clear
	m_pulse1->set_b_pin_value(1);
	m_pulse1->out_cb().set(FUNC(apple_imagewriter_printer_device::pulse1_out_handler));

	TTL74123(config, m_pulse2, 18000, .022E-6);  // first stage  (hooked up to 2 section of 74123)
	m_pulse2->set_connection_type(TTL74123_GROUNDED);
	m_pulse2->out_cb().set(FUNC(apple_imagewriter_printer_device::pulse2_out_handler));
	m_pulse2->set_clear_pin_value(1);
[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

Now 2gs beagle write will print on Standard/Best:

[Linked Image from i.imgur.com]